New

So I'm still fairly new to the game. I understand the system of this game. I've played similar games. My only real question is that I've been playing around in the vs ai just to get the feel of the game, I've played a few actual pvp ones already, but I can't decide on a main toon to play. I really like Shyvana and Nami . I've never had any real problems with them. I'm also getting a feel for Ashe . I'm still working on getting the rep to buy Shyvana and Nami but I've already bought Ashe. I've read numerous guides on how to run all three of them, but I can't decide on which one to run as my main. Any suggestions on the three that I've mentioned or any of the others I should try?