Considering the quality, the feel and the price.... Here's what I think.
There is almost a Bessa with every mount type with several adaptors available. Just see what Cameraquest has for you. The trying part is picking one. However, since the latest and greatest are the m-mount models, and at least 4 M-lens brands to choose from, the choice is clear. It is the R2A or the R3A, depending on which frame-lines are desired; and you can always buy both! You may believe the newest RM versions are better, and perhaps so, but what about the lack of auto exposure? Oops. Back to the R2A and R3A. There you go.