What SLR brand would you prefer?

What would you prefer? Nikon? Or Canon?

Pentax. If you think there's a difference, look at Lomography's range.

I 'd prefer a Hasselblad. But I'm happy with my Nikon.

I prefer Canon. I've shot Canon since about 2001.

I prefer Canon because it fits my needs better than Nikon. Canon produce better lenses, especially their primes and telephoto lenses. Canon's 35mm F/1.4L, 300mm F/2.8L IS and 400mm F/2.8L IS are far beyond the quality of Nikon's offerings. These are three of my most used lenses.
I prefer Canon's ergonomics, that's the reason I first chose Canon over Nikon. Canon cameras feel better in my hands, I've recently had a chance to play with the Nikon D800 and D4 and I hate them both. They don't feel comfortable in my hands and everything seems over-complicated, the menus, button layout, dual dial system - it seems counter-intuitive to me.

However, Nikon's bodies are far superior to Canon's. Up until the release of the 5D Mark III and 1DX Nikon was completely dominating Canon are pretty much everything related to sensor performance. This is due to Nikon using Sony sensors and Canon still trying to produce their own on top of body/lens/printer/scanner etc.manufacturing.
But, to be honest, that doesn't really bother me. The real world difference regarding dynamic range and ISO performance isn't nearly as much as the internet will lead you to believe. The 1DX is superior to the D4 and D800 when it comes to high-ISO performance. The 1DX is on par with the older Nikon D3s.

The real place Canon have been lacking in compared to Nikon has been autofocus systems which Canon have now corrected with the 5D III and 1DX.

I plan to stick with Canon because of the speed, high-ISO performance, comfort and amazing lens collection.

Pentax

Since all SLR cameras do exactly the same thing, shoot film, I'd prefer then one that will hold up the longest. There's lots of moving parts in an SLR camera and if those parts are made of plastic I think I'd not buy that particular camera. For me it's always Canon. Film handling is important and Canon and Nikon both seem to have it down to a science.

Why do you want a film camera opposed to a DSLR -Digital Single Lens Reflex?

Film cameras (SLR) can be available used from people like B&H Photo and Adorama Photo