They are both pretty easy. After phase 1 Ala'kir is a joke, and pretty much everything up to phase 3 and tank kiting the adds the proper way is a joke for nef. So idk. Id prolly have to go with nef though. Better gear and you get tier.
Al'Akir is really RNG based fight. Really annoying one. We spent 2 days on Nef and downed him on third, next week we killed him on 2nd attempt, 3rd week on 1 st attempt. Al'Akir on other hand is pain in the butt. We spent like full week on him, finally downed him, but it usually still take us 3-4 attempts to kill him again. Also he is really 2 man healable, just tried this strat yesterday, took us 2 attempts and we had 2 new people in group from "casuals" because some of our team was on Easter holidays. 2 healers and 7 DPS make first phase really fast, we got only 1 wind blast.