Prospector is definetly the better miner for AMDs RX than sgminer:
https://bitcointalk.org/index.php?topic=2033185.0

Prospector 0.0.5 alpha: 20,2-20,4 MH/s @1350/2100 @RX480
Never seen the Reddevil before over 2x,x MH/s.

And it has alpha status again. More is possible.
Stable by me with 17.7.2.