I have an M3 and an M6. The M3 is ideal for 90mm and usable for 135mm. The 35 goggles are a nuisance on the M3 so the 35 Summicron will probably go.. I use the M6 with a Voigtlander Skopar 2.5/35. I think that the M6 is more suitable for 28-50mm. The M6 framelines a a bit too small for the longer lenses, in my opinion. It all depends upon which lenses are more important to the photographer.
I love my M2, the 35mm frameline is wonderful. Now to get a better 35mm lens, at present I'm using a Summaron. Not bacd, but not a Summicron.
If you don't want to stand behind our troops, please feel free to stand in front of them.
Only 1? While I used to have a pair, sent bubba off to a new home, one is enough to keep me grinning and my over abundance of lenses vying for attention.
One Leica you ask? Easy.
Deep in the darkest heart of the East Texas Rain forest. Apprentice Analog Activist.
... And to paraphrase Yoda, there is no how, only do.
I don't have any Leica, but if I were to get one it would the M6, good combo of modernity and price. If money were no object, then it would be an MP. I shoot slide film a bit, so a good meter is critical.
M2 because I like the 35mm framelines and the smoothness. It's a real joy to use. I can vouch that the m4-2 is indeed the worst built leica. Mine has needed 4 different repairs in that last 12 months. Repairs alone cost me more than the camera.
I'd opt for the MP, because well... that's what I ended up getting. I got it because I wanted a camera that I knew I would keep/use forever. Great camera, love the shutter - it doesn't create any movement of the solidly built body. It's dead simple to use, even re-loading film. I can actually load it faster than my Voigtlander R4A!