I have tried several rear surround speakers to go with my Vandersteen 3A Signature main speakers and Vandy VCC-1 Signature center channel. The speakers I've used include the Vandersteen VSM-1's (wall mount); Coincident Triumph Signatures (on stands); and the M&K SS-150 THX tripoles (wall mount). In my audio/HT room, the speakers must be mounted behind the listener. Given this requirement for the surround speakers, I liked the M&K's the best and have kept them in my system.
The other wall-mount speaker which I auditioned and liked very much is Snell's relatively new tripole surround. At $1500 a pair, they aren't cheap, but they are very well made and struck me as excellent surround speakers.