Mario: Lots of creativity, fun, varied environments and enemies and plenty of hidden things to find. I can play most of the games endlessly without getting bored.
Rayman: Same as Mario.
Mario versus Rabbids Kingdom Battle: Like the previous ones, but an even better game.
2D Zeldas like the first three, the Ocarina games and Link between Worlds: I love the 3D games, but they have too many flaws to be this. 2D Zeldas, on the other hand are simple and endless fun.
Leisure Suit Larry, Space Quest, Day of the Tentacle, Sam and Max, Heart of China, Rise of the Dragon, Willy Beamish, Gateway, Quest for Glory 1 and Gabriel Knight 1: The defining adventure games, with lots of humor, great deaths and complex puzzles.
Metal Max Returns and Metal Saga: Blasting everything with tanks and it is fucking awesome.
Wing Commander: Perfect space simulations with great action, great characters and stories and music that tells you exactly what is happening without having to look at the displays.
SNES Adventures of Batman and Robin: A perfect Batman game, captures the feel of the best comics and the animated series perfectly.
Parodius and Twinbee: Completely fucking insane parodies of shooters with lots of fun and action.
Bubble Bobble, Rainbow Islands, Puzzle Bobble, Parasol Stars, etc: Wonderful and wildly varied and surreal games that are very lengthy, challenging fun.
Super Metroid and the Prime series: Fine complements to the old Zeldas, with similar mixtures of action and exploration.
Castlevania: Rondo of Blood: The perfect Castlevania, ideally balanced, endlessly fun and very atmospheric.
Little King's Story: One of the most creative, fun and subtle games ever and completely unique.
Bloodnet: An unusual, challenging and fun R.P.G. with a complex resource management system and a great mix of cyberpunk and Gothic horror.
Grand Theft Auto: Vice City: The best game in the series, with a colorful world, great missions, lots of humor, classic '80s style and music and endless freedom.
Superhero League of Hoboken: An R.P.G. with the unique style and humor of Steve Meretsky and very complex character development.
Dynamite Headdy, Gunstar Heroes, Alien Soldier, Landstalker: I love the style of Treasure and the challenge in most of its games.
Mega Man: A great platformer series, very colorful and fun worthy of Mario, Rayman and Treasure's games.
Dark Forces and Jedi Outcast: Great Star Wars games that really capture the fun of the old movies.
Bionic Commando and Rearmed: Grappling over long pits is really exciting.