MSI Gaming X seems indeed to be the winner of this generation, but it's worth mentioning that I've heard from plenty of people that the Palit Super JetStream and the MSI Gaming X have very similar coolers, except the Palit has a bigger heatsink (being a 2.5 slot card), though I guess performance is similar between them - Palit is mostly cheaper though, so if brand/looks isn't your concern, I'd recommend the Palit Super JetStream, I have a friend who has one, and he's very happy with it.
However I'm mostly referring to cooling... if you're interested in heavy overclocking I'd suggest the EVGA cards, some of them have just insane VRM's that help overclock stability.