I usually favour Fire and Grass type starters (no offence to the Water type starters, I just prefer to use Lapras or Gyarados or Sharpedo as my Water type in game) but I'll give my opinion anyway.
Gen 1
As various others from around the internet would tell you, Blastoise is a cool turtle with cannons attached to its back. I agree, but I've only used it a couple of times. Charizard is my favorite starter, period, so I almost always choose him. On the few occasions that I don't choose Charizard, I find I get the most use out of Venusaur. Nothing against Blastoise though, I still think he's pretty cool.
Gen 2
I would have to say that Feraligatr is my favorite Water starter. I have a fascination with reptiles in general. It's design is so ferocious, so primal. I think it's badass.
Gen 3
Sceptile is my favorite starter from Hoenn and I almost always choose him, but on the odd occasion that I don't, I'll choose Swampert. I like Swampert mainly because of its typing. It's the only Water/ Ground type whose design I don't mind. I don't love it, but out of all of the Pokemon with its typing, it, without question, has the best design.
Gen 4
I always choose Infernape, no matter what. I don't mind Torterra, I think it's pretty cool, but Empoleon is the only Water starter that I don't really like. Nothing against it, but I found Dawn's Piplup in the anime to be extremely annoying and it turned me off from the entire line. I also kind of don't like the sort of pompous look it has, but given his theme, I understand why they drew him like that.
I don't hate him entirely though, I think he has one of the more useful dual types in the game.
Gen 5
I get pissed off at Ash's Oshawott in the same vein as Dawn's Piplup, but I've gotta admit, Samurott has one of the coolest designs for any Water type pokemon that I've ever seen. I really, really love its design.
Gen 6
I've gotta say, Froakie creeped me out when it was first revealed. I've gotten used to it though since its evolutions came out. I love the concept for Greninja, but I'm still getting used to the 3D graphics so its too soon to tell.
