Well I would say GW hands down especially for the mesmer spells but it's b2p so ... hmm f2p and unique don't really go together.
I wouldn't say Rohan, but then I've never endured the game long enough to get to the subclasses. Maybe there are some unique spells there but the starting tree is not very unique. I played dark elf and elf and aside from maybe a heal in place of a nuke they're pretty much the same