M6 TTL (important if you use flash a lot)
MP (2003 forward)
I have an M6 & an MP. Both are wonderful cameras. Based on what you said above I would suggest an M6 Classic. They are well built, have excellent meters, are plentiful, reasonable (ok...you define reasonable) and are easy to find competent technicians to work on them when needed.
No doubt you will receive lots of opinions and recommendations on this. Just read up and do your homework. My final suggestion is that you go to a camera store with some used M's and just try the various models. It really is the best way to select the "right" M.