I agree that a simple mechanical camera is the best!!! The pocketable aspect is less important to me, I prefer an SLR, but do have a number of rangefinders that I have acquired over the r=years. The best camera is always whatever you have and shoot with!!!
That is why I carry really small point and shoot in my jacket. It is always with me, loaded with film. Rangefinders and SLRs are too big for this purpose.