Ok, so recently I started my MRD class cause I wanna get a WAR, but now I've seen Dark Knight and would love to do that job. Should I ditched the WAR and go for DKN or stick with the WAR?

FYI: Again I have no tanking experience, been only to 2 dgns for tanking. My problem was I couldn't keep hate. Any tips for that? Like what rotation I should use? Any tips are welcome