Well, let's do by Gen too
Gen I: Charmander.
Honestly, this doesn't even require the same arguemtn as above, I just like the other two better. Squirtle is my choice 90% of the time when I play FireRed and Bulbasaur is cute whilst Venusaur is friggin awesome, so Charizard just kind of gets left out
Gen II: Totodile
After playing through the Johto region at least three times with each starter on my old broken Gold cartridge there's really no contest. Cyndaquil looks friggin awesome and is great in-game. Chikorita's plethora of early status moves make it a great support mon even if you do decide to replace it with a better statuser later on. And then there's Totodile who is stuck with Scratch/Rage and Water Gun until it finally learns Bite at level 20/21 (depending on whether you evolved it or not) And back then Bite was still Special. Great job Totodile, way to make yourself useful
Gen III: Torchic
Okay, I adore Treeko, I always pick Treeko, I will never pick either of the others outside challenge runs, ever. But then there's Torchic who's super cute and evolves into... Combusken. And don't get me wrong, Marshtomp is no beauty.... But, Combusken... *Shudders*
Gen IV: Chimchar
Okay, this thing has literally the exact same issues as Torchic, though to a slightly lower degree. Plus it mimics it's typing. Empoleon and Torterra are awesome and their starting forms are adorable
Gen V: Tepig
And again, starts cute, turns into ugly AF Fire/Fighting type
Gen VI: Fennekin
...Is basically the same as the above Fire starters, except it started awesome and became a weird mage thing, I think I already explained why I don't like this one P adequately above
EDIT: OMG, Huk, we hate like the same things when you pick it apart by generation