Back in 2010, I would've said Tsutarja, or Snivy now. But after playing the game for a few hours, it's undeniable that Snivy, and it's line, does not fit my needs. In fact, it fainted so many times I said "Screw this" and put it in my PC for good.
After that fiasco, I tried Tepig/Pokabu. Different problem, same solution. It was too slow, it was a disaster. First of all, against the Water-type, Tepig could barely hold a candle. It could barely survive any sort of attack that was super effective, even when it evolved, it just gained more weaknesses so I put it in my PC. There's something wrong when you loss to Burgh/Arti and you had the advantage.
So there was Oshawott/Mijumaru. To be honest, I hated it. I thought it's design was terrible. But it was the only I had yet to try, so I used it. It satisfied my taste, to say the least. Even against the Grass-type, it proved to be a worthy fighter. It didn't faint easily, without giving a fight, and it was a mixed sweeper. So, in the end I made it to the end with Daikenki.
If you couldn't have bothered to read that all, I'm picking Oshawott. The game designers obviously did not know what they were doing this time around, in my honest opinion. Which is why Sinnoh had the best starters, compared to this one.