Can you suggest what socket I should use and the benefits of that socket vs others? I'm kinda between 1155 or 2011.
Wait until Haswell (LGA 1150) around the middle of next year.
LGA 2011 is too expensive and basically pointless for gaming, and LGA 1155 is a dead socket right now, with Ivy Bridge, so the best option is to just wait.
That i7 950 isn't exactly slow or old by any stretch of anyone's imagination. You could wait a couple more years to upgrade, if you really wanted to.
Edit: Also, don't get caught up in the PCIe 3.0 hype. It doesn't mean anything for any single card configuration (and not for most dual card configurations, either. It's just window dressing and something to advertise, at this point).