Right now I own almost no Leica gear as I'm putting my kids through some expensive schools - and a man has to do what a man has to do to support his kids!
In the past though I've owned the M1, M2, M3, M4, M4P, several bottom loaders, the more common Leica LTM and M mount lenses, much of the Visoflex system, two Leicaflexes, etc. This is damned good stuff too, all of it, and I miss it. Yes other 35mm film camera systems are pretty rugged, can and do produce excellent results, (Voigtlander, Canon, Nikon, Minolta, etc. you name it), but nothing has quite the fit-and-finish and elegance of Leica in use, IMO (the early Nikon SLR and RF system is a close second). The lenses are all good to outstanding, the build quality and the ergonomics are superb. Classic Leica gear is well-oriented to the knowledgeable amateur or professional film shooter who has a good grasp of photographic basics, such as exposure, depth of field, focusing technique, etc. Leica engineers superb glass and mechanics, truly useful and sometimes unique accessories, but gizmos and gadgetry are not in their domain.
For those who like very fine gear and if money's not a problem AND if total control of the photographic taking process matters, the Leica system is the ticket.