OP was looking for opinions on F3 & F1's not the kitchen sink.
The Nikon F3 is totally battery dependent except for 1/90. It also has 100% viewfinder coverage. Metering is 80/20
Canon f1N or new F1 has mechanical speeds above 1/90 in manual and requires different finders for different exposure modes.
The original F1 and F1n are fully mechanical except for meter and have 12% metering area.
Both will fill the need for your shooting pleasure. IMO the F3 is smoother & quieter than the F1's.
I have many nice manual focus SLRs. One of my favorites is the Canon F-1. It came out just as Nikon was transitioning from the F to the F2. I find the size and shape of the F-1 less ungainly that that of the F or F2. The meter is built into the body so the standard prism finder is not so big. You get a 12 degree spot meter and a nice variety of focusing screens. It seems more common to find an F-1 with a working meter or a meter which can be serviced than to find a Nikon F or early F2 in the same condition. The F-1 and F-1n models have the older CdS type meters. With a Nikon F2 you can get a later DP-11 or DP-12 meter prism and also have AI functioning. The problem is that the F2A and F2AS models are much more expensive. The newer Canon F-1N (1981 to about 1996) has improved metering, slightly improved finder brightness and more metering modes but is missing mirror lock-up. Motor drives for the Canon F-1 or Nikon F2 are large and cumbersome. If I need to shoot with a motor and I can live with no removable finder and 3.5 FPS then a Nikon FE or FE2 with an MD12 is a lot easier to handle. Both of these cameras have interchangeable focusing screens and that makes them easier to use with slower lenses or for macro work.
Hey, there are many good cameras, such as Leicaflex SL2 or the early Canon pro models. But, and its a BIG BUT, only Nikon has the lens compatibility that spans from the beginning to the most current models. Only Nikon. And the Nikon lens are probably the best Japanese lens ever made.
So, looking for the most bang for the buck with a quality camera with many many lens options, leaves only Nikon. Question is which one. Frankly, the minimum needed, IMHO, is ability to take a picture if the battery dies or no batteries at all, and MLU. Higher flash speeds are a bonus but never ever stopped me from getting a good picture.
Thanks again for all of the very helpful comments. I am leaning towards Nikon as posted about their lens selection and the ability to use the lens with the F4S (another favorite I hope to add someday). I totally forgot that the F4S could use manual lenses, very temping but I wanted a classic square brick of a SLR. I usually near a store or town so running out of battery power is not a big problem. I have lots of battery powered gear that have much shorter battery life, so I'll just bring spares.
Hoping I can someday buy all of the mentioned SLR's in this thread.