My favourite starter from all the regions is Bulbasaur. I mean, sure. My first ever starter in pokemon blue was squirtle, but, I love bulbasaur more because it gave me more of an edge of the first few gyms in the Kanto region than Squirtle or charmander. I wasn't also a fan of the kanto grass type pokemon you'd find, which appealed me to get a bulbasaur even more! I'm also a fan of the Fire / water / grass combo, which bulbasaur allows me to also get a few my favourites: Growlithe and Lapras, and combine them with it. Its a pretty nice combo, IMO.
The art design is also pretty cool and kind of original; and its also kind of cute, IMO. <3 I also like totodile, cyndaquil, and tepig, but bulbasaur would have to be my favourite all-time starter. <3