My first starter ever was Cyndaquil.
I don't have an all time favorite starter, my favorites (in Pokédex order) would be:
Bulbasaur, Cyndaquil, Turtwig, Chimchar, Piplup, Fennekin, Rowlet, Grookey.
Out of these, the ones I like the most in their final form are: Torterra, Infernape, and Decidueye.