Let's see.... Gen 1 is tough, I like them all but my order is probably Venusaur (Tank!)>Charizard>Blastoise.
Gen 2 is Feraligatr no contest, Typhlosion is cool but the Gator is Greater!
Gen 3, Blaziken gets my vote but it is a very narrow edge over Swampert who I've probably used more often on playthroughs. Sceptile is cool but just overshadowed by Mudkip/Torchic imo.
Gen 4 is Infernape, I have mega nostalgia for him and he just beats up on EVERYTHING with that STAB combination!
Gen 5 is, uh, Samurott? Kind of a forgettable round for me.
Gen 6 is Greninja, as one of the cooler pokemon they've ever made imo.
Gen 7 was cutie grass Owlet all the way, only reinforced by Decidueye the ghost archer!
Gen 8 I'm hardcore Grookie Gang, and I stand by it - although this gen is all too humanlike for my tastes, at least Rillaboom is based off an animal that has humanlike characteristics. But the giant man-hands chameleon and "regular dude with a rabbit mascot head" just are NOT my taste at all.
Kanto - They're all loveable but I gotta say Bulbasaur
Johto - Cyndaquil
Hoenn - Treecko (Sceptile is my favorite final evolution of any starter)
Sinnoh - Piplup
Unova - I have the least amount of opinions on these, but Snivy i guess
Kalos - Fennekin (but not the rest of the line)
Alola - Litten (picked it in both Moon and Ultra Sun, but never let it evolve past Torracat... I appreciate Incineroar a bit more now because of Smash memes tho)
Galar - I picked Sobble so I guess I'll say Sobble
Gen 1 is really hard. It's almost always a tie between Bulbasaur and Charmander, but gotta give it to Bulbasaur
Gen 2: Totodile
Gen 3: Torchic
Gen 4: Chimchar
Gen 5: Snivy
Gen 6: Froakie
Gen 7: Rowlet
Gen 8: Grookey
Gen I - Bulbasaur
He was my least favorite as a little kid but he grew on me over the years
Gen II - Totodile,
Gen II - Torchic
Gen IV - Piplup
Gen V - Snivy
Gen VI - Froakie
Gevn VII/VIII - 6-way tie. They're all equally garbage.
Gen 1- Squirtle.
Gen 2- Chickrita.
Gen 3- Espeon (Pokemon Colosseum is the only Gen 3 game I own.)
Gen 4- Piplup.
Gen 5- N/A (I don't own Gen 5.)
Gen 6- Fennekin and Squirtle.
Gen 7- Rowlet.
Gen 8- Scorebunny.
Gen 1- Bulbasaur (mainly because it's the least favorite of many in that gen)
Gen 2- Cyndaquil (my favorite Pokémon over all, laong with it's two evolutions)
Gen 3- Mudkip (I liek Mudkipz)
Gen 4- Piplup (mainly cause I'm not a big fan of the other 2)
Gen 5- Oshawott (not the biggest fan of it's design, but it's evolutions look much better)
Gen 6- Fennekin (First fire-starter that isn't Fire-Fighting since gen 2!)
Gen 7- Rowlet
Gen 8- Sobble
Gen 1 - Bulbasaur - The Sprite in Leaf Green was so cute I didn't want to evolve it but wound up doing so before the Elite Four, she was also a female first try.
Gen 2 - Cyndaquil - My first starter that I ever interacted with that wasn't Pikachu cuz my cousin had yellow and gold.
Gen 3 - Torchic - First Pokemon I ever got to level 100 as a Blaziken
Gen 4 - Piplup - I love penguins
Gen 5 - Snivy - Thought it looked cool
Gen 6 - Fenniken - thought it looked cute and was sold from the first trailer
Gen 7 - Popplio - same
Gen 8 - Scorbunny - same