You might have to wait for them to get everything ironed out, but I would probably go for the 2GB version. It's going to pay off if you are gaming at the higher of the two resolutions and want to up the details.

As for the OP's question, like pretty much every hardware question, get the best you can afford unless it's one of the specialty cards that only gives you a 5% FPS boots more than another card $300 cheaper.