Well in Mass Effect 1 the combat was so dull that playing as anything but a Soldier was wildly inefficient.
Every other class was just a non optimal version of the soldier.
Not so much that it was my favorite class it was just the only one that worked.
In Mass Effect 2 everything except the Vanguard was fun. My favorite for ME2 was the Infiltrator because I love the ridiculously OP sniper along with the cloaking was just awesome.
In Mass Effect 3 the controls were so broken trying to take cover was a death sentence so the only remotely playable class is vanguard. Warp, Charge, Biotic explosion, Nova, Warp, Charge, Biotic explosion, Nova, Warp, Charge, Biotic explosion, Nova, Warp, Charge, Biotic explosion, Nova, Warp, Charge, Biotic explosion, Nova, Shoot Marauder Shields, pick a color win the game.
Adepts are also kind of good in ME 3 because with the right armor you can get your Warp, Push combo to turn around in less then 2.5 seconds and make rain biotic explosions all up in that *****, but good fucking luck against Cerberus and since you spend 60% of the game against them for no fucking reason anything except Vanguard and you're just hitting your face against a wall
So that's my mechanical choice, Personally my Soldier shepard had the best story, Sleeping with Liara, Cheating on Liara with Garrus, Liara being a total **** in Mass Effect 3, then finally letting Garrus down easy and falling in love with Samantha Traynor.
I'm sure she did other stuff too, but none of it mattered. Her favorite color was red.