I have a Bronica S2A system like Eric R used to have, and as he says, the glass is decent (and in some cases outstanding, I would add), and it's possible to build a very versatile system for not too much money. I'm the kind of person who likes to have a wide range of lenses and accessories, so this solution fits my way of working and my budget.
On the other hand there's no denying that the Zeiss glass is special. I have a Zeiss 135/3.5 Planar for my 4x5" system that is just transcendentally sharp and smooth. It would also be very easy to adapt to the Bronica, which was designed so that people using press cameras could easily adapt their lenses.
You might consider getting both--a Hassy with a great lens or two that you can afford, and a Bronica with all the other lenses you might want that for Hassy would require a second, third, and fourth mortgage.