Just like kurapika said a few posts earlier, my first starter was actually Pikachu, since my first game was yellow I loved it so much and I immediately bought red and blue, which I played simultaneously. For those I chose Charmander and Squirtle respectively xD Though I suppose if I want to get technical, I started red up just before blue, so my first chosen was Charmander :P
I chose Chespin. And I don't regret every moment of it. I love how a cute Grass type with a little leaf hat turns into a raging spiked monster. I admit, it's terrible for competitive play, but I still luv it ;D
pikachu, lv100 pikachu refusing to evolve, never completing that dex...
Then it was bulbasaur because I wanted to complete the dex in order, never able to find charmander or squirtle; anime you lied to me.
My first starter was Tepig. I started with White (Tepig), then went to Firered (Charmander), Ruby (Mudkip), Emerald (Treeko), Red (Charmander), Crystal (water-type (Cant spell the name)), X (Chespin) , Back to White (Snivy to Tepig).