If you go for the Bronica then try to find an ETRSi, you get mirror lockup and a few other tweaks over previous models.
If you want the prism then get the speed grip too, with those two on it handles like a giant 35mm SLR. The grip adds a flash hotshoe which may be useful to you - the body has a PC socket. There is a motor winder too, I've not tried it but judging by the photos and specs it would probably be heavier than the manual grip and these are not light cameras! There are three commonly available prisms - a plain one and two metered ones (AE II and AE III), the AE III has more features but I'm guessing you have a light meter already so you'd be better off with the plain one. There was a Prism AE for the original ETR but I've never seen one.
Major advantage over the Pentax is that you have interchangeable film backs. The gear is also much cheaper here than Pentax, I would have had a 6x7 or 645 but you pay almost as much for a bare 6x7 body here as for a complete ETRS or ETRSi kit.