Favorites:
Gen 1: Charmander - I love dragons, so Charmander has to be the obvious choice for me.
Gen 2: Totodile - But almost entirely because of how beastly and awesome Feraligatr is. I find Totodile and Croconaw rather ugly tbh.
Gen 3: Treecko - Probably the only starter line to be my favorite all the way through. Treecko itself is cute, but not too cute. Grovyle has by far the best design of the middle evolutions with those leaves coming out of its arms. And as mentioned before, Sceptile is a big freaking lizard with a big leafy tail.
I dunno. Maybe it just appealed to my inner, dinosaur-loving child lol. Though I will say I found Treecko harder to use than the other starters.
Gen 4: Chimchar - I remember wanting to pick Piplup before D/P came out, but would up being EXTREMELY disappointed with Empoleon (though I've warmed to Empoleon since; I think I was just put off because Empoleon has a REALLY bad D/P sprite). But I saw Infernape among the leaked evolutions and though it looked awesome. And I had a lot of fun using it when I played through Pearl. Bonus points for being based on Sun Wukong.
Gen 5: Oshawott - I actually originally liked Snivy's line the most of the three, but I switched to team Oshawott after learning Samurott has swords. Come on. It's a freaking samurai sea lion with swords. How is that not awesome? That alone made me not care much about the drastic change from Dewott to Samurott.
Gen 6: Fennekin - I'll be honest, I wasn't expecting to pick Fennekin in Y. I thought it was just okay when it first revealed, you know, cute but kind of bland. I didn't really care for Braixen when it was revealed either; I found it way too cutesy and girly. Then Delphox was leaked, and I fell in love with it. I think the wizard idea was super creative, and it helped set it apart from Ninetales design-wise, as I assumed Fennekin would pretty much just evolve into a Ninetales clone. I'm happy they didn't go that route.
Gen 7: Popplio - I thought Popplio was cute when the starters were first revealed but preferred Litten because I love cats. Then that concept art surfaced, and I was immediately put off by Incineroar and started looking at the other two. Primarina caught my attention because I actually like the more elegant, feminine looking Pokemon like Gardevoir, Milotic, Froslass, Roserade, Mienshao, Delphox, and others. And when it was officially revealed, I noticed other little touches about its design that I hadn't noticed in the concept art (most notably, certain elements that make it resemble a singer or pop star like the markings around its eyes resembling makeup or the fact that its tail and that ruff thing around its neck almost look like clothing) that made me love it even more. Now, it's become probably my new favorite Water starter, and I can't wait to use one when I pick up Moon.
Least favorites:
Gen 1: Bulbasaur - But entirely because of Venusaur. I don't mind Bulbasaur or Ivysaur. I don't know. It's just not as cool as Charizard (fire-breathing dragon) or Blastoise (turtle with big water cannons coming out of its shell).
Gen 2: Cyndaquil - I know this is unpopular opinion, but I find Typhlosion to be incredibly bland design-wise. I remember picking Cyndaquil when I first played through Silver and being extremely disappointed with it.
Gen 3: Mudkip - I don't mind Mudkip itself, but I'm not too fond of its evolutions design-wise. They're just ugly to me, but I think that's a personal thing. For the most part, I've just never been a fan of the big, bulky Pokemon like Swampert. That said, I did pick Mudkip in my first run through Sapphire, and Swampert was incredibly powerful because of that Water/Ground typing, so it's not the worst thing in the world
Gen 4: Turtwig - I still like Torterra, but I just prefer Infernape and Empoleon.
Gen 5: Tepig - I don't like pigs in general, so it didn't matter what Tepig evolved into, I probably wasn't going to like it. Also, Fire/Fighting had been done to death at that point.
Gen 6: Chespin - I never really cared for Chespin at any point during the XY release cycle. At that point, it had that "Piplup/Oshawott" type of look to it. And its evolutions didn't help matters at all. It kind of goes back to me just not liking big, bulky Pokemon in general though, so it's probably just personal taste.
Gen 7: Litten - But entirely because of Incineroar, as I actually like both Litten and Torracat a lot. I dunno. When I first saw it, I hated it because I was one of those people wanting Litten to just evolve into a big, flaming tiger with no anthropomorphic features whatsoever. But thanks to fanart, the recent trailer, and learning what a heel wrestler is, I've kind of warmed to the big wrestling tiger. Now, I'm more neutral towards it, but I think Primarina and Decidueye are MUCH better designed starters.
