Considering gen by gen of which I've liked and which I've actually used all the way. These are just personal preferences.
Gen 1 - I've usually picked Bulbasaur, for the ease of first 2 gyms while catching something reasonable on the way. I never like Charmander's final evolution. (Sorry lizard lovers.) and Squirtle... Oh god, I think this just falls to me having seen the anime episode way back then and thought how annoying they sounded like. So only 1½ points. Mostly because it's the overly hyped one.
Gen2 - Chikorita line went same as Squirtle. Saw the one episode with the possessive-over-trainer selfish Chiko and ditched the leafy dinosaur from my lists. Cyndaquil... well it was pure fire type, it had a cutesy bandwagon, but I didn't like final evo. Totodile I just thought was and enormous troll until I used it on my recent playthrough on HG. Ice Fang (later on Avalanche) and Crunch. 2½ points I guess.
Gen3 - The designs were creepy to me at the beginning. I only really liked Treecko line, because Pursuit. One of the few grass pokemon that I actually liked by looks. Torchic is okay, but I think it's wearing out on me. I've used it too many times that it's not even funny. Mudkip. All the memes. Everywhere. 1½ points.
Gen4 - Turtels. I had thought of using a grass starter at first, but then I went an looked at the stats/moves. So slow at start. ;_; So derpy face. Chimchar and Piplup are tied to me, since I used both on my first ever Diamond game (got the penguin from a trade). Both had their strong points, but the Piplup line survived more in my gaming. 1½ points.
Gen5 - I like using Snivy line. I don't find it really cripling. I'm just patiently waiting for a Contrary Snivy to be released officially. Yes, just for in-game use. I don't do competitive. I used Oshawott on my first game. It was nice, some what bulky to basically solo my E4 tries. I've yet to use Tepig. The design just puts me off. Not to mention the third Fire/Fight typing... 2½ points.