I'll offer up my experience. When I used to shoot both Tri-X and HP5 (35mm), I would rate them both at box speed and develop them both in D-76 per the Ilford/Kodak times. In doing that, HP5 was consistently more grainy. When I switched to having a lab process my film (in XTOL), it was the same thing, HP5 noticeably more grainy. That may be fine, depending on your taste, but to me the HP5 grain was a bit excessive for the look I wanted in my prints. I realize that you can reduce the grain by rating at a lower ISO and reducing development time, but I'm just saying that rated at box speed and developed per manufacturer's recommendations, HP5 was more grainy. So I standardized on Tri-X, and have been happy with that. I haven't tried HP5 in medium format, but have some 120 HP5 and will try that.
Another thing... I've never tried pushing HP5 to 1600, but have shot several rolls of Tri-X at 1600 and have been surprised at how well it pushes.
Just my experience, but it all comes down to what aesthetics appeal to you...
Dale