I would say first up that the newer AMD GPU's are no worse than Nvidia for thermals. They all fit within certain thermal limits dictated by their GPUs. Granted, Nvidia does have a pretty efficient architecture, and compared to the AMD 200/300 series, they are cooler and quieter. The AMD 400 series though is pretty good, but they don't have a true 'high end' GPU. The 480 is good, but only GTX 1060 level good.
Second, I would say that I wouldn't buy -anything- right now until Vega releases and is reviewed. If AMD utilizes some of their design ideas that they integrated into Ryzen in their new Vega GPU architecture, it could be surprisingly good. And have HBM. And be 14nm.
Third, depending on where you live having a space heater during winter months is a freaking bonus.
Alrighty, as for your question, so much depends on:
What kind of games are you thinking of playing.
What resolution are you going to be playing at.
G-sync enabled monitor?
Price Range?