Best is overall cooling is with the AquaComputer Kryographics Hawaii
IF with it's backplate
Best bang for the buck is the Watercool HEATKILLER GPU-X3 R9 290X
While evaluating the graphs one should Ignore the arrow named "BETTER" pointing to the blocks or you may get into the "subliminal message trap" .
http://www.xtremerigs.net/2014/08/11/r9-290x-gpu-waterblock-roundup/
I got the HEATKILLER GPU-X3 R9 290X. Really happy with it's top engineering and finish quality, really good VRM cooling without the need of spending an extra $ on a back plate... plus it looks so much better.