interesting questions, the answers of course are very varied, let me explain...
many old timers regard the m3, m2 and m4 as the last great Leicas, and everything after that are just mass machine produced copies with enhancements. If you read old Leica websites and enthusiasts articles, the sentiments about the post M4 bodies are quite spot on. And among the old greats, the m4 standout as the zenith of Leica technical accomplishment. (you can read this article from the Leica Historical Society of America (can you imagine, a bunch of people meeting, presenting and debating about leicas ? just like this forum except that the LHSA are old foggies and get special discount from Leica....
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http://www.jimarnold.org/downloads/leica/leicaM4.pdf
So, many older enthusiasts, the choice is M4 followed by the M3 and then the M2 with cheaper parts. Of course, many will flame me for putting the m2 behind the m3. Actually it makes sense, old foggies have bad eyesight and the m3 with the .92x is really a blast to focus. Even beats all the current Ms... Perhaps this is one reason why the Leical MP has the M3 rewind instead of the M4-M6 modern type of rewind lever.
Talk to any Leica enthusiasts born past 1975 and they all say its the M6 or the M6 TTL or even the M5. The M6 is quite identical to the M4-P except that it has a light meter. Having a light meter solves alot of guess work since the eyes can fool us even to seasoned Sunny 16-ers. But light meters will fail eventually, much sooner than the mechanical body. What's worse than failing outright is failing slowly, producing inaccurate readings, and posting a lot of "What's wrong with this negative ?" postings on the forums. If you have a cheap camera and the camera fails, you replace it. If the M6's light meter fails, the replacement is gonna be quite expensive.
I am somewhere in between, born before 1975 but only started photography for the past 18 months and Leica user for the past 12 months.
Actually, I sold off my m3, m2 (frankenstein) and m4, and bought a M4-P. Because I like the fact that it has a hot shoe, and also because it doesn't have a light meter so I don't have to worry about batteries etc. I use a Sekonic 408L light meter. One strong reason for the M4-P for me is that it was cheaper than the M6 but has all the bits I wanted (hot-shoe, 6 framelines etc). (Funny thing about price, when I bought the M4-P, the price was USD 400, now the M4-P is touching USD 1k, which was the price of the m6 last year. The recent prices are crazy now. Blame it on the burgeoning Asian middle-class...)
While most Leica folks will be quite indignant about using flash, shooting at available light has its limits too. The early M could do M and X flash but it was generally a pain as you'd need a cable which interfered with your viewing.
Hope I didn't confuse you too much. But I try not to prescribe what is best for you, only describing what works for me.
My only advice is this: Buy the camera that you are sure of using consistently. And save up money for film, the price is going up.
raytoei
