If you enjoy shooting 50mm and 90mm lenses, there js nothing on the planet more exquisite, accurate, and pleasant than a Leica M3. I am just a 50mm shooter, and using an M3 safeguards you against the feeling of the need to upgrade to a better camera.
With a Voigtlander Heliar 50mm f/3.5 or a Summilux-ASPH (pricey!) you will be at the pinnacle of what is possible with 35mm film, with a small camera that never has to leave your side.
Used to have a very extensive Olympus OM system, but for most types of photography suited to 35mm, the M3 makes me happier than ever. Focusing speed and accuracy is unbelievable compared to an SLR.
I have used Nikon SLR's for years. Still have and love my FE and my original F, but I now use mostly my M3 with a 50 mm 'Cron and a Circa 1937 Leica 90 mm lens. Camera Heaven.