Preliminary comparison: F-1 original (1971) versus F2AS (1977) versus F-1N (1981)
Solidness: F-1 by far. The Nikon F2 feels less solid than the original F, and a quick test for this is trying to squeeze the top plate flange sides with your fingers. In the F2 they can be squeezed. The F-1 and F-1N can't.
Overall the wall thickness of the top and bottom plate of the F2 are surprisingly light and thin for such a camera!!
Canon F-1 wins here over a large margin.
Smoothness: Shutter vibration and film advance equally smooth between the F-1 and F-2, a pleasure to use.
Viewfinder: Markedly brighter on my F2AS, but i'm suspecting this is due to having a 1977-state-of-the-art screen and mirror, so it's not a fair comparison. Would need a 1971 F2 to properly compare.
Nikon wins here by a large margin, with a brightness equal to the one on my F3.
However, the F-1N(1981) viewfinder is even brighter!
Ergonomics: F-1 and F2AS have great ergonomics overall. Can't decide.
Viewfinder mounting: I'd say improved on the F2 over the F. About equal; i'd say viewfinder is quicker to remove on the F-1, but screens can be removed without touching them on the F2.
Preliminary Verdict?
I will probably keep my just-acquired F2AS forever; it''s everything i want in a Nikon camera. The F3 will be sold, i think.
I love my F-1 and will keep it forever as well, if i had a brighter screen it would be perfect; probably the F-1n (1976) has a much brighter screen and I can just replace the one on mine with the improved version.
I think at the end it's a tie and this match would be decided by the lenses, and i'm a bit partial to the Canon FD and FL line over the Nikon Ai and Pre-Ai lines. Back in 1971-1973 the Canon FD lenses were generally more technically advanced than their Nikon pre-AI, K-series counterparts (sometimes FAR advanced), but afterwards Nikon counterattacked with the Ai line (and their improved optical designs and coatings.)