Kanto - Squirtle line. Charmander and Bulbasaur are my favorites, but Squirtle is... meh. Rather boring.
Johto - Cyndaquil line. To me, Cyndaquil and its evolutions were always kind of weak.
Hoenn - Mudkip line. Boring. Next.
Sinnoh - Chimchar line. Another Fire/Fighting-type starter... yay. >_>
Unova - Oshawott line. I don't like their designs, and their names are kinda derpy.