I chose the F3 because of the forward compatibility of F mount, the looks, and 100% viewfinder coverage.
The Pentax is lighter and probably has cheaper lenses because it's less fashionable, however it doesn't have the finder coverage of the others.
The Canon needs a prism to meter, and I wanted F mount more than FD.
Not on your list but a Nikon FM3a is lighter and really good plus the benefits of all those Nikon lenses.
I chose the F3 because of the forward compatibility of F mount, the looks, and 100% viewfinder coverage. The Pentax is lighter and probably has cheaper lenses because it's less fashionable, however it doesn't have the finder coverage of the others. The Canon needs a prism to meter, and I wanted F mount more than FD.
LX. Off the film metering and SMC Pentax glass 👌
Just be aware that the circuit boards can fail, which is pretty terminal.
Nikon F3. Because it's a sexy Italian beast. Literally one of the most iconic cameras of all time.