Yes, it's a little bit of an odd topic, and a bit of a throwback, but the old Gamecube Controller is still relevant. (I shall most likely ramble a bit.)
First, let us consider controllers as a whole. From the Atari to the XBox360, (disregarding the Wii Remote for now), it is acknowledged that to decently control most games, you need a directional control and at least one other button, for actions. As games increased in complexity, more buttons became necessary. The NES probably [citation needed] started the trend of thumb-controllers as we know them, with the left thumb controlling directional input, and the right thumb controlling other actions. Canonically, in a platformer, A to jump, and B to attack. As games became more complex, more buttons were added, with the SNES laying down the standard D-pad, 2 shoulder buttons, start, select, and 4 main action buttons. Finally, as gaming entered the 3rd dimension, more controls were needed, notably the re-introduction of the analogue stick (and later, two of them) for precise movement and aiming.
Now, finally, the Gamecube controller. With all these controls, how to possibly keep them straight? How to accommodate them all on a single chassis? How to make it possible to access them in one convenient grip? Nintendo learned from their N64 controller that while ergonomics were important, all the buttons must serve a purpose, and be accessible. (Microsoft addressed this problem by not addressing this problem, and simply made their original controller enormous.) Sony learned from this too - the Playstation 2 controller featured, within (mostly) easy reach, 4 main buttons, a D-pad, 2 analogue sticks, and 4 shoulder buttons. This controller is a fine design that has clearly stood the test of time. However, I argue that the Gamecube controller surpasses this with one key observation:
Not all buttons are equally important.
In most games, one button will be hit more often than any other. The Gamecube's massive A-button, while appearing toy-like, serves the purpose of centering the thumb on its main task. It is most often hit with the side of the right thumb. The second most hit button, the B-button, is positioned perfectly to be hit with a quick, easy, yet decisive motion with the TIP of the right thumb. This decisive position is necessary, because B is almost always the ATTACK button. Also, its secondary position to the left of the A button makes it easily identifiable as the "cancel" or "back" button in menu screens. Simply rotating the thumb to the sides gives access to the X and Y buttons, which have a definitively secondary shape and nature, and represent the wild cards. Special moves, dedicated jump commands, weapon switches, etc... They feel like an alternate action, yet require no shift of position or actual movement of the thumb to access. Thus, the canonical 4 main buttons are easily accessed by simply rotating or tilting the thumb, and are easily identifiable based on importance. This serves to make controls in most Gamecube titles extremely INTUITIVE and easy to learn, severely shortening their learning-curve.
Contrast this, if you will, to the main buttons on a PS2, XBox(360), or SNES controller. From the get-go, one is uncertain of the position their thumb must be in, what button it should by default rest on, and it is even possible for a novice to get "lost" on their own controller in the heat of things!
Now consider the Shoulder and Trigger button. The XBox managed to keep a trigger-like design, yet Nintendo lost this with the form-factor shift from that of the N64. Thus, the Z-button is shifted to rest next to the R-button. This is a double-edged sword, as now it is hit with the right finger, a more common trigger finger, but it doesn't feel as trigger-like. With the multiple shoulder buttons of the PS2 being more often than not confusing, redundant, and unnecessary, the Gamecube has only an L and an R button, with the option of squeeze-sensitivity, with a definitive "click" at the end of the squeeze. These 3 buttons certainly get the job done, but some may miss the old trigger design of the Z .
Nearly all games require only one main directional input, so it is unnecessary that the D-pad and the main analogue stick be simultaneously available. (The PS2 acknowledged this as well). The C-Stick is a bit of an odd color and design, but it serves the purpose of optional camera control, aiming-stick, and n00b-stick (Smash Bros. lingo). Its position, as on the PS2, necessitates a physical move of the right thumb off of the main buttons, so most games use it in secondary capacity. This is where the logic of the PS2's multiple shoulder buttons may prove superior - in games which demand dual-analogue control, the player is offered one more button. (While the Gamecube players have L, R, and Z at their immediate controls, PS2 players have L1, L2, R1, and R2).
As far as the size is concerned, my hands are perfectly suited to the Gamecube, and I have about average hands for a man (an easy 10th interval on a standard piano keyboard, 11th if I reach.) I can play Gamecube for hours on end without discomfort, but I have heard complaints from one of my larger-handed friends, who prefers the PS2 controller for this reason. The shift to the wireless Wavebird takes a few minutes to get used to, but doesn't affect the experience.
All in all and overall, I consider the Gamecube controller to be the best traditional controller to date, particularly for its realization and design philosophy that not all buttons are created equal. No other conventional controller is as intuitive and natural, and intelligent in its design. While it does have its flaws, it has and will stand the test of time, as everyone knows that many Wii games still play best with the ol' Wavebird.
First, let us consider controllers as a whole. From the Atari to the XBox360, (disregarding the Wii Remote for now), it is acknowledged that to decently control most games, you need a directional control and at least one other button, for actions. As games increased in complexity, more buttons became necessary. The NES probably [citation needed] started the trend of thumb-controllers as we know them, with the left thumb controlling directional input, and the right thumb controlling other actions. Canonically, in a platformer, A to jump, and B to attack. As games became more complex, more buttons were added, with the SNES laying down the standard D-pad, 2 shoulder buttons, start, select, and 4 main action buttons. Finally, as gaming entered the 3rd dimension, more controls were needed, notably the re-introduction of the analogue stick (and later, two of them) for precise movement and aiming.
Now, finally, the Gamecube controller. With all these controls, how to possibly keep them straight? How to accommodate them all on a single chassis? How to make it possible to access them in one convenient grip? Nintendo learned from their N64 controller that while ergonomics were important, all the buttons must serve a purpose, and be accessible. (Microsoft addressed this problem by not addressing this problem, and simply made their original controller enormous.) Sony learned from this too - the Playstation 2 controller featured, within (mostly) easy reach, 4 main buttons, a D-pad, 2 analogue sticks, and 4 shoulder buttons. This controller is a fine design that has clearly stood the test of time. However, I argue that the Gamecube controller surpasses this with one key observation:
Not all buttons are equally important.
In most games, one button will be hit more often than any other. The Gamecube's massive A-button, while appearing toy-like, serves the purpose of centering the thumb on its main task. It is most often hit with the side of the right thumb. The second most hit button, the B-button, is positioned perfectly to be hit with a quick, easy, yet decisive motion with the TIP of the right thumb. This decisive position is necessary, because B is almost always the ATTACK button. Also, its secondary position to the left of the A button makes it easily identifiable as the "cancel" or "back" button in menu screens. Simply rotating the thumb to the sides gives access to the X and Y buttons, which have a definitively secondary shape and nature, and represent the wild cards. Special moves, dedicated jump commands, weapon switches, etc... They feel like an alternate action, yet require no shift of position or actual movement of the thumb to access. Thus, the canonical 4 main buttons are easily accessed by simply rotating or tilting the thumb, and are easily identifiable based on importance. This serves to make controls in most Gamecube titles extremely INTUITIVE and easy to learn, severely shortening their learning-curve.
Contrast this, if you will, to the main buttons on a PS2, XBox(360), or SNES controller. From the get-go, one is uncertain of the position their thumb must be in, what button it should by default rest on, and it is even possible for a novice to get "lost" on their own controller in the heat of things!
Now consider the Shoulder and Trigger button. The XBox managed to keep a trigger-like design, yet Nintendo lost this with the form-factor shift from that of the N64. Thus, the Z-button is shifted to rest next to the R-button. This is a double-edged sword, as now it is hit with the right finger, a more common trigger finger, but it doesn't feel as trigger-like. With the multiple shoulder buttons of the PS2 being more often than not confusing, redundant, and unnecessary, the Gamecube has only an L and an R button, with the option of squeeze-sensitivity, with a definitive "click" at the end of the squeeze. These 3 buttons certainly get the job done, but some may miss the old trigger design of the Z .
Nearly all games require only one main directional input, so it is unnecessary that the D-pad and the main analogue stick be simultaneously available. (The PS2 acknowledged this as well). The C-Stick is a bit of an odd color and design, but it serves the purpose of optional camera control, aiming-stick, and n00b-stick (Smash Bros. lingo). Its position, as on the PS2, necessitates a physical move of the right thumb off of the main buttons, so most games use it in secondary capacity. This is where the logic of the PS2's multiple shoulder buttons may prove superior - in games which demand dual-analogue control, the player is offered one more button. (While the Gamecube players have L, R, and Z at their immediate controls, PS2 players have L1, L2, R1, and R2).
As far as the size is concerned, my hands are perfectly suited to the Gamecube, and I have about average hands for a man (an easy 10th interval on a standard piano keyboard, 11th if I reach.) I can play Gamecube for hours on end without discomfort, but I have heard complaints from one of my larger-handed friends, who prefers the PS2 controller for this reason. The shift to the wireless Wavebird takes a few minutes to get used to, but doesn't affect the experience.
All in all and overall, I consider the Gamecube controller to be the best traditional controller to date, particularly for its realization and design philosophy that not all buttons are created equal. No other conventional controller is as intuitive and natural, and intelligent in its design. While it does have its flaws, it has and will stand the test of time, as everyone knows that many Wii games still play best with the ol' Wavebird.