Kona - no direct experience, but looks to be a good bike for a good price.

Redline - Heavy. Inexpensive - complete bike for less than some frames. Mixed bag of parts: some good, some junk. Rear wheel spacing is 110mm (BMX) as opposed to 135mm (Mountain).

Surly - own one. Love it. For my type of riding, I think it handles great, better than my Ibis Mojo. Good price considering you get a frame AND fork. Decent weight.