If it's your main camera, get an M and just adapt LTM lenses to it. If it's for a collection then yes a Barnack has it's advantages and can be fun to shoot with.
The 105mm or 135mm will give you less in focus tehan the 55mm, but a longer working distance. Best bet is stopping down or focus stacking multiple images.
I'd say go for a Canon VL or something from that generation of Canon rangefinder bodies.
S2 is a good shout too, lenses are cheaper, even if there is a smaller selection.
I like the bodies preceding the P, the V/VL/VT.
Cameraquest has a great piece on them comparing them: https://cameraquest.com/crfl1bl.htm
The P actually just removes a few features but gets recommended a lot due to how common it is.
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