I think that the Pentax SuperProgram / SuperA is one of the better under-the-radar cameras out there right now - fairly cheap too. I like it better than the Pentax ME or ME Super as you can use it at full auto, aperture or shutter priority, or full manual. I really like shooting in aperture priority mode. I bought one recently with a 35-70 zoom for $25. I have another that I bought new in 1985. The K-mount Pentax lenses haven't shot up in price like the M42 Takumar lenses or old Nikon glass, yet they're great lenses.
Of the Canon AE-1 or Nikon FE, I'd go with the Canon simply because the lenses are going to less expensive. Both have very accurate metering. The AE-1 is a historic camera being the first to incorporate a microprocessor. There were also a number of manufacturing milestones with the AE-1 with its reduced parts count, modular assembly, etc. It's the camera that put Petri, Topcon, and Miranda out of the camera business. They simply couldn't afford to invest in the R&D that the AE-1 incorporated.
Back in the day a very good friend of mine bought a brand new Pentax ME Super Program camera when they came out. He was wanting a Pentax zoom lens really bad but couldn't afford it. I recommended a Kiron to him but he thought I didn't know what I was talking about. He finally went to the local pro shop to find out what they had to say and of course they sold him one. He ended up being thrilled with the lens. I remember him framing a beautiful 11x14 shot of the Arch and Eads bridge taken with that lens.
My favourite A-series camera is the AT-1. Designed for overseas markets only (no domestic Japanese sales), it was a full manual camera when the prevailing fashion was for automation. There are a number of things going for it, match needle metering, modern readily available batteries, a huge shutter speed dial around the wind on lever, light weight - and it's dirt cheap nowadays.
The AT-1 is an anachronism, functionally from a previous era, in a polycarbonate body - the exact opposite of my T90. Anyone looking for a manual camera that doesn't weigh a ton or require re-jigged metering circuits could do a lot worse.