I don't like comparing regions, but for each generation, here is my favorite:
Squirtle
Totodile
Mudkip
Piplup
I'm not a fan of Water-type Pokémon, really. But with starters, they all seem to be the coolest ones.
@ Shadowdragon: What do you mean Chimchar has advantages over the others?
Also, if it's about starters in general, this should be in the Pokémon General forum.