I have a Hydros Pro and several BP/W rigs.
The Hydros is more comfortable, more stable, quicker to don/doff, and quicker and easier to adjust. BUT, all those things are only very small improvements over a properly setup BP/W.
On the other hand, the Hydros has a lot of plastic and monoprene. If somebody accidentally drops a tank on the waist belt buckle, or a shoulder strap quick release, that Hydros might be done diving for a while, while you're waiting for parts.
Despite being just slightly less comfy, stable, etc.., I would take a BP/W on vacation, because mine have no plastic anywhere on them (except the plastic parts on the wing, like the OPV, elbow, etc. which is no different than the Hydros). Nothing on the BP or harness that can really break. Having less concern over something getting broken by another diver with an uncontrolled tank is good peace of mind for me.
And, my BP/W has D-rings and retention loops everywhere I want them, in the exact places I want them.
They Hydros doesn't have pockets, and it also does not have any conveninent way to do something as simple as clip off a light and secure it so there's not a loose end dangling and swinging around. Or a way to clip off my (very large) camera rig lanyard. I clip it to a waist D-ring on my BP/W. Or a good spot to clip a reel and SMB - necessities for ocean diving.