" Is disc priest, rdru, and rsham still fun to play?"
No, yes, and no.
Honestly I want to say no because Legion made me borderline suicidal after just one season, but this game is super fun when you've just come back to it for a few months, it's whether you'll last past the honeymoon period that becomes a different question entirely. I'll spare you the amount of farming you'll have coming up if you want to play again though. HF.