Well this is a big question.
Venusaur ties with Sceptile
I don't know. Honestly, Venusaur probably would have won this one if I wasn't having a spell of Sceptile-liking and remembering using him on an Emerald play-through going on at the moment. Bulbasaur is arguably my favorite Kanto starter(still fighting with Squirtle for that spot occasionally) and while Sceptile isn't my absolute favorite of the Hoenn starters he is a pretty cool Pokémon.
Swampert over Blastoise
While Blastoise is a great Pokémon(my second favorite Kanto starter) and I could never hate the awesomeness that is the Squirtle Squad, Swampert still pulls this one out. He's my favorite member of the Hoenn stable and just a really cool Pokémon in general(have you read his Dex entries?) with a sweet design, memorable and non-irritating cry, and a cool real-life basis. Not to mention that Mudkip was the first starter Pokémon that I ever actually used in a game that was mine(sharing that "my first Pokémon" slot with Cyndaquil). Also, M-Blastoise my bring more cannons, but M-Swampert brings the beef.
Charizard ties with Blaziken
I used to be crazy about Blaziken. I really did. I even went so far at one time to call it my favorite starter and my favorite Pokémon overall(don't know what I was thinking, really). But know, all theses years after the Deoxys movie that made it look so cool, after I had actually used it so long ago in Emerald, and after it has gained so much hype for being the first starter to go Uber and having such a ridiculous Mega Evolution.... I don't like it that much anymore. Don't get me wrong, it's deign is still kind of cool(even if it is a bit sullied for me) and I still remember Blaze Kicking the crap out of everything in Hoenn back in Emerald but honestly he's on the bottom of the Hoenn starters for me. And Charizard is on the bottom of the Kanto starters. What's funny is that he's gone the opposite route of Blaziken. I used to actually hate Charizard because it felt so incredibly overrated by such a large number of people. It just felt like it was soaking up so much of the spotlight for having what I thought(even as a kid) was a meh-tasting design and a bad spot in the TV show(why would I want a Pokémon that would either cremate my face or take a nap each time I need it?). He's cool because he looks like a dragon? I'd always thought that Dragonair is the coolest dragon-like Pokémon from Kanto. Buuuut... those feels have subsided. I don't have a vehement distaste for Charizard any more. He's an okay Pokémon who is maybe just a bit overrated and has two pretty cool Mega Evolutions. Still, both of these guys are at the bottom of their starter groups to me.
Winner: Hoenn