Starter Opinions, huh?
Generation 1...well, I mean, they're the classic ones, you can't really bash them.
First of all, I like how all of them were similar animals (reptilian), gave them a nice cohesion that some of the later Generations lacked. We've never had this again---Gen II has two reptiles, and a mammal, Gen III has two reptiles (well, I guess an amphibian, but close enough) and a bird, Gen IV has all different animals, and Gen V and Gen VI have two mammals, and a reptile/amphibian. I'd like to see Gen VII go with all mammalian Starters, personally.
Individually, it's sort of random trivia I think a lot of people forget that our first ever Starter Bulbasaur was dual-type...Grass/Poison...something that hasn't been done since then. Of course, that's probably because it perhaps muddies up the Type Triangle a bit---most dual-types would offset it---and new players might've wondered what relationship Poison had to the Type Triangle way back when. Anyway, Bulbasaur is an extremely solid design, resembling a real animal slightly but with enough imagination behind it to make it interesting and a neat gimmick that I think set the stage for Pokemon. I feel like Bulbasaur is the Starter fans appreciate more as they grow-up.
Charmander is the most-loved one, and no surprise---it's Fire, a "cool" type, and a reptile that becomes a dragon, it's pretty much an extremely safe design, and while I think the Pokemon has gotten a bit too much publicity lately for my taste, I'll admit as a child I picked him easily as my first Starter.
Squirtle's kind of weird. The other Starters in Generation 1 have a nice, cohesive evolutionary path---Bulbasaur's bulb sprouts, and Charmander grows horns and wings (although the color shift to red for Charmeleon, and then back to orange for Charizard, sort of bothers me) but Squirtle's is kind of murky. It grows these ears and tail which is pretty weird (it's based on a Japanese folk creature and all, but probably confused many kids), and then just loses them in place of realistic cannons? Blastoise is a Pokemon that has a very solid, instantly likable design, but I gotta say he's kind of weird.
Generation 2 suffered the same issue Johto as a whole did, it just couldn't live up to Kanto. The Johto Starters aren't bad, but they're easily overshadowed by the Kanto Starters in every way...it's no surprise at this point they went with the Legendaries to advertise the games over the Starters. My biggest issue? All monotypes. I think it's what made them feel very dull. I guess you could say there's a nice cohension in them all being pure, unlike Generation 1 which had a weird division with two dual-types, one which was dual-type the entire way through, and a monotype, but I still wish they were given a secondary type. On the other hand, while I think Feraligatr being Water/Dark would easily fit given how Bite and Crunch switched over to being Dark-type attacks (but perhaps they didn't want to grant a new Type to a Starter), I don't know what Types you'd give Meganium or Typhlosion as they're designed now except perhaps re-using Grass/Poison for Meganium.
Chikorita I think suffers the most from feeling like a second banana to the Kanto Starter. It's the first Starter I think you could say is "gendered" as a female...from a design standpoint, it has a much more stereotypical feminine appearance, and the anime ran with this. And, I think for a lot of fans, that was probably sort of a negative for them. The Starters in Kanto all became pretty tough looking and intimidating, and Chikorita offsets that by being very cute. It also sort of just does the whole "dinosaur creature + plant element", and doesn't really do anything to stand out. I like Grass-types, but Chikorita has never done anything for me.
Cyndaquil is pretty weird. Back in Johto, it didn't stand out too much, but now it feels pretty off-kilter compared to the rest of the Fire Pokemon in its color design, going with a dark Blue you wouldn't expect to see paired with the Type. It's also the first Starter to ditch the reptilian theme (although at first some might mistake it for some weird lizard if they're not familiar with what it's based on, as I did as a kid when I first saw it), which makes it unique compared to Charmander. It has the simplest design throughout its line, basically just getting bigger, and perhaps might be a bit too dull for a Starter? It's a nice Pokemon that has fans, but it almost feels like a Pokemon you'd find in the wild as opposed to a Starter.
Totodile is my personal favorite Johto Pokemon, but doesn't really stand-out either as it feels like Squirtle 2.0, just with a different animal. It's the most colorful of the Johto Starters...the other two are pretty dull colored in their base forms, but Totodile has a really bright and colorful scheme that is like what a lot of Johto Pokemon went with. Its design feels a bit more fluid than Squirtle's, evolutionary-wise, as it doesn't randomly add anything than drops it, except perhaps the "caveman" pattern on Croconaw which goes back to the chevron Totodile had with Feraligatr. But yeah, I think if they made him Water/Dark, that would've been neat.
Generation 3's Starters are pretty cool, I feel like most people can agree on that. Perhaps some might even say they're the highlight of Generation 3? They feel more unique than the Generation 2 Starters overall, with a return to some neat Dual-typings (except Sceptile till ORAS came around), and some pretty interesting designs, for better or worse. It also helps they each got signature moves---Leaf Blade, Blaze Kick, and Muddy Water---and were the first Starters seen with Abilities to stand out more.
Treecko is my favorite, and it's not hard to see why...like Charmander he goes for an easy "cool design", a gecko with leafy appendages, and it works. Yet he's managed to avoid being too overexposed for me to not feel dorky liking him. Like Chikorita though, he suffers from Grass-type Starters being a bit less creative than the others, for years basically being a reptile + a plant element. He's different enough from the past two visually though to curb this a bit...Venusaur and Meganium both give off sort of a passive impression with their plant features being seen as more decoration, while Sceptile's plant elements are much more aggressive in appearance. Unlike the other Starters, seems like everyone agrees Grovyle is cooler than Sceptile.
Torchic I think gets a lot of mixed feelings. It feels more traditional for a Fire Starter than Cyndaquil (and started the notion that Fire Starters were the most fluctuating of the Starters in terms of basis), but also introduces a major change for Starter Pokemon overall that causes a lot of feelings to this day...the humanization of Starter Pokemon. Before Blaziken, every Starter had a very animalistic appearance, but after he appeared, it seems humanoid animal Pokemon became the norm for Starter Pokemon, culminating in Generation VI of course, and Pokemon in general seemed to include more of these types perhaps due to how popular he proved to be. Pokemon has had humanoid Pokemon since Day 1, and I don't mind them, BUT typically the older humanoid Pokemon were specifically humanoid and didn't really resemble any animal. Alakazam, Hypno, Mr. Mime, Machamp, have animal-like elements, but you can't really look at them and say they're a specific animal that's been humanized. Blaziken is a humanoid rooster, Lucario is a humanoid wolf, Greninja is a humanoid frog, etc. I don't mind this too much, but I can understand while it bugs some folks. Blaziken though is fairly inoffensive and in retrospect is fairly benign, and has at the time a really neat dual-type, Fire/Fighting, and design that's also a pretty good pun on a "cockfighter".
Mudkip has the meme on his side, but I always thought most people didn't really care for him beyond that, going with Sceptile or Blaziken. Like Venusaur, I've grown to like Swampert perhaps more than the others, especially since I legitimately dig his Mega and think it almost should've been the normal design, but I can see why he might have put people off. He's weird as a fuck looking, and it's hard to know what he is exactly. In my opinion, people, especially kids, will probably move towards the Pokemon they can quickly decide which animal it is...Charmander and Squirtle have the advantage over Bulbasaur, for example. Mudkip is an axolotl-salamander creature, which isn't exactly mainstream. He's the first Water Starter to be dual-type, Water/Ground (which while not overused by Starters, is pretty common---in fact Johto had a Water/Ground salamander in Quagsire, and there's another Water/Ground line in Hoenn in Barboach and Whiscash) which was neat, and since the anime pushed the idea that Electric is the natural enemy to Water Pokemon, it's neat having a Water-Pokemon that resists that to me.
I'll do Gen IV, V, and VI in my next post.