If your objective is to make photographs, as opposed to retaining or building collectable value, I'd go for an M6 classic or an M6TTL for several reasons. First, being newer, they will last for many years before needing repair. Second, being newer, they have better coverage with respect to viewfinder frames, and offer choices of viewfinder magnification. Finally, there is less fetish-factor with the M6/M6TTL, so prices are more realistic. Even though I rarely use fill flash with the Leica, I opted for the M6TTL for the few times that I do so.