Mostest for the Leastest
Bronica SQ/SQ-A, SQ-Ai, SQ-B
Mamiya RB67 Pro S, SD
My advice? Get the newest version of any of these bodies in the best shape you can afford. Same goes for film backs--ratty condition=heavy use/age. Most of those listed above sold well over several model generations with largely interchangeable lenses, backs, finders, etc. Be picky and patient and unafraid to build kits from pieces over time. Example? I wanted an extra 120 back for my Bronica SQ-B. Looked for ages but auction candidates were always extortionately-priced and/or smoked. Found a boxed, mint one last month for $30. Happy!
Many here will differ but older isn't necessarily better--it's still older. Getting service on any film camera is getting harder and pricier as time ticks by. Keep that in mind as the endorsements for old TLRs and folders roll in. I like reliable, working cameras with few, if any, age-related issues--present or potential.