If you only use Medium Format, I think 35mm will help you in having the camera with you in more circumstances, or in having with you a larger set of lenses with the same weight.

Small range-finders in particular, such as a Leica M but also a Minolta CLE, or a Contax G1/G2 as suggested, can enter within a small bag with an entire set of lenses, let's say 21, 28, 50, 90 or 24, 35, 90 for instance. The weight and volume is going to be very small.

I would personally prefer to buy two cheaper bodies (such as Leica CL, Minolta CLE, a second-hand Zeiss-Ikon etc.) instead of just one. That would drastically reduce the number of lens-changing operations (which are always a nuisance) or allow to go round with two different kinds of films.

The advantage of the small format is that it is small. The technical quality of the picture depends much more on the lens than on the camera. Expensive cameras are OK if you have "excess money" to spend in photography. Otherwise I would concentrate the expense on the lenses, going for less expensive but quality-wise perfectly functional alternatives.