A couple of years ago I decided to get back in to film and got a pretty good deal on a EOS 1n and a EOS 5 with Eye control focus.

The 1n is awesome. Really heavy though. It feels like it's made of cast iron. The 5 is pretty good too. I have no complaints and they both work perfectly with my EF lenses. I'd happily recommend either of those.

If you wanted to go entirely manual/mechanical then you're probably looking at something older or a Nikon FM (I think?)

I do also have a Pentax KX from the dark ages and it's lovely to use but the light meter is stuffed so I have to use an external one which isn't really that practical sometimes. I only have one lens for that camera too which limits how creative I can be, more so than the Canons.