I like HxH but I never enjoyed it as much as most readers seem to do. I don't like it more than OP or FMA (unless we're talking about the original anime, which I would place below HxH). Haikyuu I haven't read, and I'm not interested in it either, so it goes last on my list.
I struggle with FMA and OP. I love both series for different reasons. There are things in which each surpasses the other.