Depends on what you want to spend, how big/small.
* Yashica GSN (GTN - black), probably the best value. Good ones can be found for $0 - $50. Aperture priority, great lens, fantastic almost spooky metering, very fast in operation, easy to find, no need to adjust voltage of battery or film speed, faster film speed rating (25-1000), parallax corrected rangefinder, shutter reportedly quieter even than the Leica, unique ability to meter and hold shutter open up to 30 seconds, good stepless Copal shutter, good (not great but solid and usable) rangefinder, and an outstanding 45mm/1.7 lens. It also seems to hold up better than most. Spend the extra $20 and get one that's been serviced and has had the POD replaced. (own)
Konica S2 - Large manual FLRF, I don't own this one but enough people brag about its lens to assume it must be very, very good. $30, $40, $50 ??? Depends on condition.
* Konica Auto S3. Just happened to fininsh a roll of Tri-X with this very camera today. Very small, with a renowned 38mm/1.8 lens that was rated as the best semi-wide ever tested by some photo mag when it came out. Reported 62-82 center resolution over all apertures, including wide open. It also has a cool fill-flash metering system. Shutter priority only, no manual override. Very quiet shutter. Perfect street shooter all in black. Diminutive, about the size of the palm of your hand. One of the last and perhaps the best of the fixed lens wonders from Japan. This one will cost you around $100. Somewhat rare.
* Lynx 14e. BIG camera. BUT it's 100% manual (meter, of course), and has the fastest lens ever slapped on a fixed lens - the seven element/5 group double gauss 1.4 Yashinon. It is a very good lens, usable at 1.4 but flare prone. Great low-light shooter.
Minolta 35 SP... Great lens, only JFLRF with spot metering.
Oly RD - small, well-made, manual control but expensive and hard to find.
Oly RC - slower 2.8 lens but folks seem to love this camera. Easy to find, not expensive.
Canon 17 QL III, another of the more popular fixed lens rangefinders. Manual override, well made, shutter priority.
* Yashica Electro CC - another great aperture priority model from Yashica. Much smaller than the GSN - Leica-like in black, with an infamous 35mm/1.8 lens that's hacked off the body and made into Leica M mounts in Japan for $500 US. Hampered by a max shutter speed of 1/250 and speed cap of 400 ASA. Still a great camera, a bit hard to find.
Pick one, but expect to send it out to be CLA'd or repaired. Trust me, it's money well spent. Try not to get "GAS" once you buy one of these. They become addictive and soon they will "multiply" like rabbits. While I like each of the ones I own, truthfully, they all take great pics, are pretty similar, and had I stuck with the my first GSN I would be quite satisfied.
* cameras I own