I romanced Ashley in the first game, but she really pissed me off at Horizon. I can't believe that she wouldn't even talk to me for more than 2 minutes, just because I was working with Cerberus. So, I think ready for my male shep to move on.
I'm at the point in the game where I can pursue Tali, Jack, or Miranda.
So, what's the best relationship (story-wise) for my character? Or should I stick with Ashley and see if anything happens in ME3?
It's your game, play it how you want. And Bioware has said that the 3 possible romances from the first game will return in the 3rd game (well, except for the one that can't return because of the choice made in the first game). So it's up to you it you want to stay loyal to her, or move on. Either way, you'll deal with Ashley in the 3rd game.
Money saving tip: Since it costs 2 cents to share your thoughts, and you only get a penny for them, just stop talking.