Good Morning, Chris,
I very much like my Fuji 6 x 7 rangefinder and the Koni-Omega system. The Fuji, however, is expensive, and the Koni may be hard to find in a limited secondary market.
A TLR (Autocord, Yashicamat, Mamiya, Rollei) would probably be easier to find; condition is more important than particular brand. A decent TLR can produce excellent results.