Gen 1: Charizard. Gen 1 starters aren't that interesting to me anymore, but Charizard holds a special place in my heart, since it was my starter the first time I ever played pokemon.
Gen 2: Feraligator. Simply because I don't like the other two starters as much.
Gen 3: Blaziken. It's fire. It's fighting. IT KICKS.
Gen 4: Infernape. It's fire. It's fighting. IT'S A MONKEY.
Gen 5: Emboar. It's fire. It's-- okay you get the picture.
I haven't really played these next gens yet, so I'm just gonna base it on appearance (and maybe some fan games with gen 6-7 starters).
Gen 6: Chesnaught. IT'S AN ADORABLE GIANT SPIKE BALL, WHAT MORE IS THERE TO SAY?!
Gen 7: Decidueye. Edgy. And ghost.