Here's how I see it...
The HxH anime stomps on the OP anime, out of the big shonen titles (Naruto, OP & Bleach) , HxH has the best anime adaptation. Overall as a series, HxH is just good. It only has 2 amazing arcs, one of them being near perfect which is the YorkNew City arc but the Chimera ant arc was really good but it had it's flaws (slow start & asspulls at the end). The heavens arena, greed island & election arc were good arcs, not amazing. The rest of the arcs are either average or just meh. That isn't enough to place it over series like OP. I don't HxH has reached to that feat. yet. Now that being said, the dark continent arc is simply amazing. The amount of dialogue & content we get in each chapter is a lot for a chapter. If togashi can keep that consistency & greatness that the dark continent arc is showing, then it'll prob. be as good as OP if not better! However one small complaint about the dark continent so far is that it seems that Togashi just slaps on a sh*t ton of dialogue. I mean some of the heavy dialogue either feel pointless or just can be summarized pretty easily due to the excess amount of words. It seems like OP is the only series that can do heavy dialogue chapters right.