For me i picked Charmander because of its final evolution Charizard, i know different moves that can counter many other type of pokemon and it can make charizard really strong for a example Charizard can learn earthquake and dragon claw and earthquake do a lot of damage to fire type pokes and then dragon caw does a lot to dragon type, and also its my favorite starter there is.
I picked Charmander too, mainly because I love fire pokes, and I'm guessing you like Charizard judging by that massive flapping Charizard animation. xD I don't even use my Charizard anymore though, and he can't be traded so he is just stuck in my PC.
I picked squirtle mostly cause charizard is way to over rated and competitive wise is the worst starter (Not including Mega). Might have angered people who picked charmander (sorry). I also like water types which is why I picked squirtle over bulbasaur. But bulbasaur is still Awesome
I picked Squirtle; I've always chosen water pokemon for my starters in every gen but gen 3 due to the beginning type advantages when it comes to gyms and knowing that obtaining water pokemon would be difficult without a rod/surf.
I picked Squirtle because it was in the middle...or was it in the middle Shorty after, I quickly deposited it and never used it.
I picked Cyndaquil as my Gen2 starter. However I didn't get a starter for Generation 1, because I lagged out of the buidling.