I didn't really dislike either as I was only running them as healer. Since Alwaysreap, while more annoying, is easier (I have not seen a wipe there even once, and I've been running these since the second week of the expansion, so most people there were new and only clad in lowest possible iLvl), so it balanced out with the more enjoyable fights but higher difficulty of Fractal.
Then I got a 9-day streak of ONLY ALWAYSREAP! Which really made me fed up with the dungeon and its mechanics, also it was later, so people stopped dying in Fractal, so one of the advantages was gone.

And now I have finally hit 60 on DRG and went into Expert roulette, ofc got Alwaysreap, and the untargetable mechanics are SO FUCKING ANNOYING! It's almost on the same level of annoyance as The Vault. Also I really have no idea how the phases are triggered, but they feel really short for example on the first boss, I can't count the amount of times I lost Blood on him.