I had a SQB with 80PSB, 150PS and 150S (the 150s not at the same time), a prism, a couple of backs and other bits and bobs. I eventually sold it all and bought a Hasselblad (501CM with 80CB).
Looking at numerous 8x8 prints from Portra 400VC/400NC/800 from either camera I cannot say I see much difference in sharpness. However, I do see better contrast and colour from the Hasselblad but this could be down to the subject matter and how the lab printed the shots. This is very subjective though as the subject matter is obviously different, I never shot both in parallel. I am just making an overall observation over numerous prints that I do like the Hasselblad look better. But if I was stuck with the SQB I would certainly not be unhappy.
What is very different is the feel and build quality of the two systems. When I first got hold of the Hasselblad I was stunned by how solid it felt. The lines are very clean, nothing protruding and everything is very smooth and nice. It really does feel a solid chunk of camera with everything fitting perfectly flush with everything else. The Bronica, on the other hand, looked and felt like a number of bits put together with bits rattling (the WLF was a source of constant noise) and the switches feeling, well a bit loose. The winder somehow always seemed to pop-out or catch on things and I had to turn back and fold it. The body is also more blocky and less comfortable to hold for my hands (but this is very subjective).
Overall, the advantage of the Hasselblad, for me, is the body: it just feels nicer. And I like to think that the 2-3x price the Hasselblad cost me gives me better contrast and colour
It is a huge difference in money though. For the money a 501CM+80 kit goes in the UK you can get yourself a SQA, grip, WLF, prism, 50, 80, 150, a few backs and still have money left. And then, you have the mechanical vs electronic shutter issue. Which one is "better", is open to discussion. I cannot say anything about reliability for either system, I had no issues with either of them.
In any case, if I was stuck with a Bronica I would most certainly be happy with it and wouldn't constantly think "oh I wish I could afford a Hasselblad".