So, as you said, multiple companies have come out with single piece, drop forged halligan. I carry a pro bar. I wouldn’t change it for a thing. To me, a well tuned pro bar is the best. However, we carry the Paratech single piece hooligan at my part time. It’s obviously better than the 3 piece but i feel it still has its flaws. To me the forks are still a little to thick. 

I havent used the leatherhead. That’s what our department has started buying to replace our 3 piece halligans lately. I know very respectable guys like Arthur Ashley that endorse it and also helped design it. If he says it’s good, it’s good. The only negative I’ve seen looking at it is it’s hexagonal shaft instead of octagonal like the pro bar. The hexagonal shaft puts an edge in line with the shoulders so if striking the shoulders is something you might find yourself doing then it’ll be harder than the smooth surface of the pro bar. 

Fortunately, the worst offender of SPF halligans, the tri bar, by Akron brass has been discontinued in its original form. I’m not even sure they make the second generation of it anymore. 

Min my opinion you can’t go wrong with a pro bar and the leatherhead is a very close second for me.