I'd get the less expensive one. In all likelihood, it overclocks well, close to, matching, or exceeding the factory overclock of the other model. Even if it doesn't reach it, the performance gains could quite minimal from game to game.
I'm a huge fan of EVGA these days. They RMA'd, free of charge, a gpu I broke. I explained exactly how I broke it, provided pictures of the damage, and everything. I love 'em.
Sorry, I don't mean to sound like a commercial or anything, but the company really did a nice thing for me, so I have to share.
Free games shouldn't normally influence your choice, but if you like a free copy of Batman Arkham City... many models include it. I got it free with a evga card. It's actually the Steam code for the free download. I haven't played it. I heard there's a patch in the works so the highest settings don't cripple the rig.
You linked 3 different models of cards. A gtx460 for $180, gtx560 for $200, and a gtx560ti for $210. If those are the choices, go with the gtx560ti. The prices are close and it's faster than gtx560 which is faster than gtx460.