I made a list from the beginning of this thread till now. I collected everything depending on GPU type, H/s and W. Almost all listed cards have modded bios or clocked to best Hash/Watt ratio.
I hope I got everything right and of course everybody is telling the truth

listed in order of efficiency:
7950/280 290-300H/s @ 200W
7970/280X 300-310H/s @ 210W
290/390 395-400H/s @ 260W
290X/390X 400-410H/s @ 260W
Fury/FuryX 450-460H/s @ 275W
RX 470 290-300H/s @ 110W
RX 480 300-310H/s @ 90W
Nano 450-460H/s @ 175W
While Claymore performs best on Windows - the other miner performs best and stable on Linux ..... I was on Windows before but now on Linux and I ain't going back!