For SoD (I’m horde side, could be different for Ally) basically any class we’d be like “Hell yeah, welcome” except Rogue. I don’t know why but we are constantly overwhelmed with new rogues joining and people making Rogue alts.
Also the most common class to message me when I’m LFM DPS for dungeons
I really think any other spec you want you could find a guild that needs it pretty easily.
(Viable specs though. A few things don’t work like Arms Warrior. Just a DPS issue)