Gen 1: Charizard is the obvious fan favorite. Blastoise is second, with Venusaur being the "Unloved Starter" of this generation.
Gen 2: Probably Typhlosion, but Feraligatr is a close second. For Meganium, see "Venusaur" above.
Gen 3: I agree that most of them were evenly liked. Sceptile and Blaziken were the two main competitors, simply because the people who didn't choose Swampert hated him. At least in my school, "So I herd u liek Mudkipz" was considered overused and very annoying. However, since the Speed Boost Torchic was distributed as an event Pokemon in X and Y, and nearly everyone got to use him, the main starters being chosen for OR/AS are Swampert and Sceptile.
Gen 4: Infernape was by far the most popular, Empoleon was second, with Torterra being the least liked. Torterra, unlike Venusaur, wasn't considered dumb and wasn't hated, but he was just less popular than the others.
Gen 5: The most hated generation starters. The most popular (but that's not saying much) is probably Serperior. Samurott is second, but there's a gap. Then, the lowest of the low, arguably the most hated starter, is Emboar. Three fire/fighting in a row? Come on, man. Plus, the thing is a horrible Pokemon. Slow but strong. However, he didn't have the proper defenses to survive more than 2 hits. Basically a worse version of Torterra.
Gen 6: Greninja is the most popular. No contest. Chesnaught is cool, but even he can't make up for Quilladin's ugliness. Then there's Delphox. Fennekin got screwed over. Everyone was expecting him to turn into some awesome fire wolf, but instead we got... well, Delphox. I get that the theme is the main classes for an RPG (The Warrior, the Mage, the Thief), but still.
Gen 3 and 4 are probably both good contenders for this. Gen 1 is kind of iffy, though. It feels like there's more people who are fans of Blastoise and Venusaur than people realize. It's not that Charizard is overwhelmingly popular so much as Charizard fanboys can't shut up about it.
You have a point. I think that Johto is split more than the others, but not to the same extent as hoenn. People really like all three. If not for the event torchic, lots of people would be picking that for ORAS too.
NOBODY likes Chikorita.
This. Chikorita is generally considered one of the worst starters, if not the worst starter, in the entire game. Considering its counterparts, that says something.
i wont disagree with chickorita being the worst of the 3, but it is the most "adorable" according to my gf. and it gets razor leaf at like lvl 8? thats a strong start.
my favorite has always been cyndaquil though.
"when I'm in the process of doing something, I do it not because I think it's worth doing, but because I'm trying to MAKE it worth doing."