Reviving this old matter as I stepped into Bronica last year and would like to share my experience as a former hasselblad-owner. I cannot help to compare but as things even out somehow between the systems I think that's ok.
I bought a used GS-1 as the square never felt right to me and ai always ended up framing and printing square to. Cropping on the other hand always brought me to what I felt were the limits of the resolution I needed.
In the hand the GS-1 handles like a wider Hassi and feels less refined but that's a small price you pay for the larger format. The finder of the GS is not as bright as a Hassi with Accute-matte screen but beats the Hassi with standard screen. The GS-interlocks are perfect and prevent you from doing wrong anything. In the hand the GS feels less refined and a bit more rattly and plasticy but still pretty robust and utilitarian. Magazines are not as smooth to operate but lack any felt/foam-seals which will deteriorate over time like on a Hassi.
Lens-quality is flawless with the PG-series. I now own five lenses and have only good words to say about them. I owned 50 CT (great center, stop down to at least 11 for sharp corners), 80 F (great), 150 CT (great), 250 CT (good), for the Hasselblad and they were a mixed bag in comparison, ranging from good to really excellent. The Bronica PG-line seems more evened out to me, missing part of the wow-factor as well as the limitations of some of the older Zeiss-designs I had used back then. I could never afford the newer Zeiss-designs from the F-line (used to have a 2000fcw) let alone the highpoints in wideangles with floating elements or the 100, 180 and 250 SA and sure don't want today, after the market went crazy.
Shopping for GS-bodies and lenses in Germany was astonishingly easy. The 50 mm was the only lens I had to buy from abroad and cost more than 250 € and turned out worth it. The others kept popping up around me and I will be picking up the 200 mm as No. 6 in the lineup to complete my system this week. Sourcing small bits can be more difficult. I had a correction-lens for the AE-finder custom made as the market for the right dioptrien for aging eyes has dried out.
Looking into current Hasselblad-offerings there is hardly any of the desirable bodies with GLS-mirror and user-interchangeable screens avaible and they are about five times the price.
With respect to reliability everyone will tell you a Hasselblad will last a lifetime. Well, that's a lie if there is any. It will bei repairable but will fail and with lenses and magazines I can assure you that they will need "maintainance" on a regular basis while a Nikon F2 would keep klicking away happily. Ok, so it will be repairable. Good luck with that. If you find a dependable repairer stick to him. I had been burned more than once with a crater carved into in an inner element of my 5.6/250 mm after a shutter-overhaul being the worst experience and a set of two A12s still not stopping at frame 1 when coming from the shop being the nail in the coffin of my love for the system.
Every part of the Bronica-system has worked without much trouble so far. Contacts needed cleaning for the AE-prism, that's it. But if it fails, that will be the end if parts are needed and I haven't heard of anyone around working on them anyway. I will solve this problem should it occur.
So this is my take on the story: The Hasselblad is the better camera, if the format is right for you, you hunt down one of the more recent bodies (501cm, 503cw, 200(0) in good shape) that will not block part of the finder with long lenses, flip in a brighter accute-matte screen, combine it with their best lenses and be willing to find a good shop to keep it in shape. I could see myself doing this, I loved my 2000 fcw, pictures from it are hanging around me, but adding price to the equation I just take a look at the GS sitting in my bag and put a wide smile on my face and feel the love for Hasselblad fading into the past.