Hi Rob, sorry to hear about your illness but great to see you back on the forum.
Not sure which Voigtlander you had but I used to use an R4M and it seemed pretty solid - but definitely not as solid as the M4-P, M6 and M6TTL I've owned and used in the past.
Which Leica, for me, depends on which lenses you intend to use with it. Most have different combinations of framelines and, unless you intend to switch lenses (an expensive exercise) the best thing is to have a trawl through the internet to find which Leica model best fits your lens (collection). This site might help:
https://www.cameraquest.com/mguide.htm#M7 2002-
If, like me, you use wide to medium focal lengths (28mm-50mm) then the best value for money is probably an M6. If you can stretch to an M6TTL or M7, they are better (in my opinion) as far as metering is concerned. If you want meterless, I've always had a soft spot for the M2 and M3 - but check which lenses they are able to accommodate.
There are many more experienced Leica users on here, so expect some sound advice. Otherwise, have fun looking and I hope you find your ideal camera.
Best wishes, Paul.