MA,
A lot depends upon what you want to photograph (where you are going) and where you are coming from. The Bessa has a GREAT viewfinder, bright and clean. It has a built in meter which is handy for many people. Leica Ms are rock solid, take bumps and keep on ticking. Will remain very repairable for many years. The both feel very different in your hands, but both (at least IMHO) feel good. I have to admit I like the Bessa feel with the winder attached much better than the plain Bessa.
The hand built quality of a Leica M2/3/4/4-2/4-P/5/6/MP are second to none. You are paying for fit, finish and robustness.
With the economy in the tank, prices on used Leicas are much lower than say two years ago. New and used Bessa are hovering around the same place they were at that time. This is not because they are better, just priced lower and many options still available new.
Please remember you need to think about what lens to start with. There are many great options you can find new today (CV, Leica, ZI) and even more classic used (Nikon, Canon, etc.).
There are many other great Rangefinders out there beyond just Leica and Bessa. I LOVE my Nikon RF, sold off all my Leicas and Bessas to keep her. Canon has some world class classics (e.g. Canon P) and there are others.
There are great M2s and M3s out there at great prices, but do you want/need a built in light meter. You can get this in a Leica (M5/6/7) for a bit more money. I love working with an external meter so the fact that my camera does not have a built in meter is not a show stopper.
I've learned that for me Nikkors and CVs give me a perfect blend and a great look. Each lens has a unique signature. You might like ZI glass or all CV.
Starting with a Bessa and a 35mm CV lens (2.5, 1.4, 1.2) will not serve you wrong.
It's hard to recommend what is best without a lot more info.
Either way you will not go wrong.
B2 (;->