I have owned quite a few medium format cameras. My Hasselblad 500cm is my favorite over all. I have a bad back and the Blad is not hard on me to carry around.
I used to have a Mamiya RZ67. It was my favorite medium format camera for portraiture. It's fantastic as a studio camera on a tripod. I eventually sold the kit to help fund a 4x5.
If you buy the RZ make sure you get the 110mm. It's a real gem!