When I first played Ruby, I chose Swampert as my starter because all of the other ones seemed weak to me at the time (I was a young age, so...). He actually turned out to be really good, and I grinded him up to Lv.100 by the time I got to Steven.
In LeafGreen, a couple months after beating Ruby, I chose Bulbasaur because it was like my favorite Pokemon at the time. I grinded him up to Lv.100 once more, but even then I couldn't beat the Elite Four... >_<
Wehn I got my hands on Sapphire, I was a bit smarter. I chose Torchic this time for a fresh experience, and did well.
Then I got FireRed. I hated how I could not beat the E4 in LeafGreen, so my instict told me to go for Squirtle because of how well Swampert had done. Good choice for me. I beat the game with him and an Articuno.
And of course, I finally got Emerald. Looking for a new and fresh experience, I chose Treeko. Bad choice. I was stuck on Flannery for a while and I'm still trying to beat Steven. Oh well.
Overall, water starters sit well with me.