All of them perform well, HOWEVER, The Vapor-X is voltage locked and has crappy VRM cooling.
The IceQx2 has the best overall cooling but spreads air in your case and the normal IceQ vents the hot air out of your chassis.
Really depends on your usage. If you are considering Dual-GPUs, the IceQ is great for keeping ambient temps down. Single GPU the IceQx2.
Vapor-x I would not suggest unless you do not OC at all. Instead a better Sapphire option is Dual-X versions.