Canon F1 or AT-1?

Looking to get my first SLR after shooting on point and shoots the past few years. Going to have to learn how to expose properly and other beginner things. I found both of these for the same price but unsure which to go for.

I'll be taking this camera on the road all year so I want something reliable like the F1 but worried it'll be too heavy. However I've heard better things about it and I kind of like the idea of having a very durable beast of a camera that'll last forever. The simplicity and lightweight nature of the AT-1 does seem like a positive though.

Both have been recently serviced but the F1 body is cosmetically in bad condition while the AT-1 is in great shape all around.

Mostly will be shooting documentary type photos, very run and gun. Any advice is appreciated.