Not familiar with Ippo but...
Berserk to me seems like the closest to an ending. Guts is at Elfheim and a lot of long running plot lines will be wrapped up there. One has to remember Guts' goal is not to kill all of the God Hand, just Griffith. Femto is his goal. Void is merely curious of his actions and avoidance of causality. Slan is enamored with Guts, either in a sexual way or with a desire to own him. Conrad and Ubik don't seem to care or matter to Guts' story. It's pretty much impossible to give an actual time frame on when Berserk will end due to hiatus but I'd say it is close to 75% complete.
One Piece is the most consistent of the three by release schedule and a canonical halfway point - Fishman Island - was passed years ago. What remains to be seen is what the actual end point of the series is. Right now there are clear marks that must be defeated before the end - Big Mom and Kaidou. Blackbeard, Akainu and maybe Shanks are the others but they will be saved for further down the road. I doubt it is Raftel, and even if it does end up being the end there is zero chance One Piece wraps up without a second Marineford-like conflict to once and for all settle the World Government score.
Hunter x Hunter will never fucking end. Like lets be real here. Togashi could have ended it 10 chapters ago when Gon and Ging met up, but he didn't. Sure there would be plot lines abandoned and character arcs unfinished but it would at least be over. There's no chance for that now. The Dark Continent Arc looks to be as long if not LONGER then the Chimaera Ants Arc, and there is zero chance the DC Arc will be the final unless it turns out Meteor City was in the Dark Continent all along and the Spiders and Jairo are just waiting there which doesn't make any sense. I've given up hope for a conclusion to HxH.
