It was the gen 7 starters for me because I thought all of their designs were visually pleasing. Rather disappointed with Litten’s final evo though, as I was counting on a four legged fire cat but oh well. I eventually used all of them in replays (Sun, Moon, Ultra Sun).
Kanto: Pretty much always choose Squirtle. Charmander is a tough early game choice and Bulbasaur struggles against all the very common Poison Pokemon. Squirtle has always been reliable when I need it and is by far my favorite.
Johto: I pretty much only like choosing Chikorita, simply out of love for the design and it being a clear underdog in need of some more appreciation. No, it's not the best choice for the Gyms/E4 but it honestly can and will do way better than it gets credited for. I know Whitney is rarely if ever much of a struggle. I do occasionally choose Totodile because it's all-around reliable. Not a fan of Cyndaquil in general.
Hoenn: Torchic is the only answer for me. Mudkip is a quality choice in how strong it is, but I don't care for the design of its evos as much. Treecko just never seems to be very good IMO.
Sinnoh: This is where I genuinely like all 3 and enjoy mixing it up a lot. All 3 have super cool final forms and do well in-game for the most part. My favorite however, is certainly Piplup.
Unova: I really like all 3 despite their shortcomings and relative unpopularity, but Snivy is my go-to. It's surprisingly reliable even with its typing and move pool. Emboar is just a bit too slow to count on sometimes, and I have never had a good experience with Samurott despite how cool it looks.
Kalos: I only like choosing Fennekin, but you can't go wrong with any of them.
Alola: Popplio by leaps and bounds. The other two are cool and all, but Popplio is such a precious cinnamon roll.
So by process of elimination I'd say Sinnoh, just because I like all 3 so well, but at the end of the day I still have a clear favorite in every generation.
Personally, it was the Kalos starters. but not because i love them all. personally, i found them all lackluster and boring. i choose fenniken, because i don't like chespin evolutions and froakies cool, but greninja is incredibly overrated. as for a trio that i love all of them, i'd say alola. i'd also say kanto if charizard didn't exist. but i do know my choice for alola, and thats popplio
Honestly, I tend to gravitate heavily towards one starter in pretty much all the games except RSE.
I generally prefer Treecko to Torchic, but I'll easily flip-flop between them depending on how I plan on building the rest of my team. Mudkip is my least favorite of the three, but I don't hate it. I just don't want to have it become an HM slave like all my other water types in Hoenn because I'm too lazy to go back and forth between PCs
the kanto starters. i honestly like all of them and i hardly have any preferences at all for any of them. with the other regions i'm 100% sure of which one i like best but with kanto i find it hard to decide.
Sinnoh starters, for sure. While I hate Piplup (thank you Dawn) and is meh to Empoleon (though it does have a good typing), I'm always torn between Turtwig and Chimchar. However, as all of the other Fire-types in Sinnoh suck, Infernape usually wins out, but I love Torterra so much. If possible, I try running both of them, but generally I have bit of a dilemma when it comes to Sinnoh starters, so that's the one I voted for.
Second place goes to Kalos, usually between Fennekin and Froakie. Normally, I dislike the Water starters and always favor the Fire starter, but Greninja proved its skill and versatility to me to give my love of Fire starters a run for its money. At least Kalos has decent options for Fire-types, so going with Greninja doesn't hurt me much. Plus, I like ninjas (who doesn't?). But, generally speaking, in Kalos, it can often be decided with a coin toss as both Fennekin and Froakie are good options.
Every other time it's pretty easy for me (in gen order: Bulbasaur, Cindaquil, Torchic, Tepig, Litten, Scorbunny). Yes, I do favor the Fire-type quite a bit more than the others in most case scenarios, with Bulbasaur, Turtwig, and Froakie being the exceptions in that regard.
For me, the hardest choice is between the Sinnoh starters. With other regions, the choice is easy:
Kanto: Charizard is an easy favorite.
Johto: Same with Typhlosion. Although I like Meganium too, it's not overly useful in Johto games.
Hoenn: I easily like Sceptile the best, so Treecko is an easy choice. I'm not really a Blaziken fan myself.
Unova: I like both Samurott and Serperior, so basically this is the second-toughest choice, because I'm always having difficulty to choose between the two. Tepig is never really a serious option for me.
Kalos: Delphox is easily my favorite. I'll choose it over Greninja any day.
Alola: I've been a fan of Primarina ever since it was revealed. Easy favorite.
Galar: I loved Cinderace from the moment I saw it. Again, easy pick.
But the Sinnoh starters are all very solid. At least in their final stage designs. I've just always picked Chimchar, because Sinnoh doesn't have that many Fire types, so choosing the Fire-type starter is the easiest way to get one. Plus, I also like having a Fighting type in my team, so that helps too.
The first Pokémon game I ever played was Black, and I went with Tepig. This Tepig would only go onto become a Pignite, because I lost the game cartridge.
But I also love Oshawott and Snivy. Oshawott is just adorable; Dewott looks great; Samurott has swords(okay that's not actually why I like Samurott but I can't really explain what it is that I do like about Samurott). Snivy's whole evolution line has something about it that I can't help but love.
So my choices are my first ever Pokémon, the cutest otter around, and Snivy. Not exactly an easy choice to make.
It's the Sinnoh starters for me! I don't particularly care about any of them, so choosing's a pain and I more-or-less pick at random. If I had any sense I'd be picking chimchar because Sinnoh has a major dearth of options when it comes to fire-types, but I'm so apathetic about the Sinnoh starters I can't even bring myself to care about type match-ups.
(For the record: bulbasaur, totodile, mudkip, ???, snivy, froakie, litten, sobble)
Definitely the Hoenn starters since for me the three are consistently awesome in all of their forms. Blaziken, I admit, I'm not a huge fan of and I think it is a bit overrated, but I can't deny it is very strong and useful, and my Lord Helix, that Mega! Despite this, overall the Treecko line is still the coolest and my favorite.
And since I'm actually using a girl Grovyle in a ongoing nuzlocke (my first ever) I'm even more attached to this line. Yes, I did get a female Treecko. That is cool since it makes her more unique. I hope she doesn't die though!
The starters I care less about are the Sinnoh ones because I have yet to play a game in Sinnoh.
Wow I'm stunned my pick is near the bottom for others:
Kanto: Picked Charmander as a kid, that's my Gen 1 starter for life
Johto: Straight typings across the board, I go with fire. Cyndaquil is cool enough, it works!
Hoenn: I don't like fire and fighting. Water / Ground is amazing, Mudkip it is!
Sinnoh: I DON'T like fire and fighting. Water once again gets awesome typing, with Steel? Plus it gets the by now traditional Ice moves to wreck the Pokemon who is supposed to be strong against it, but now they're 4x effective? AND that Pokemon has relatively poor special defense, and is slow, and the water starter is a Penguin, and Penguins are awesome? Piplup, and easily!
Unova: I DON'T LIKE FIRE AND FIGHTING! UGH! I actually agree, this is easily the weakest set of starters, they're all terrible. Went with Snivy though because a grass type Pokemon that outspeeds the water starter, isn't centered around physical attack, and has HP recovery moves is at least half-decent, and if not now, when?
Kalos: This was the pick for me. They're all unique, and interesting, and all of them are cool and effective on a playthrough team. How are you supposed to easily pick? Went with Fennekin personally, since it's the best Fire starter in a long time, and Fire starters are the best starters. Even still, Chespin and Froakie are both awesome and frankly that's the one set that to me just begs you to do multiple playthroughs. Am I alone in this?
Alola: All of them are new, which makes them interesting, but in my opinion not nearly as strong as the previous set. Decidueye doesn't seem to know what it wants to be, and is a slow split attacker with glaring weaknesses and poor health recovery. Primarina is not my thing, stylistically. So Litten is the easy choice.
Galar: Straight typings is an easy pick for Fire starter, and Scorbunny does not disappoint.
Edit: I realize that some of the Pokemon I think are terrible will be the favorite Pokemon of all time for others. That's cool, you do you! We all have our own tastes and preferences, and whereas Primarina is not my thing at all, it might be Exactly what someone else is looking for. So just note that just because I don't like them that doesn't mean I think they are unlikeable, I'm not trying to attack anyone's preference, much less someone for having that preference. Just throwing this disclaimer out there because I know some folks can get defensive about their starters and I'm not trying to hurt anyone's feelings here