I have owned these:
1. Spyderco Military - big, light, ergonomic, and pointy -- great slicer
2. ZT 0303 - tough, strong, heavy, more of a sharpened prybar
3. Junkyard Dog II - smaller than the others, little clunky, there are better choices in a mid-sized titanium folder
I haven't owned these:
- Fallkniven PXL - seems very nice, but pricey
- Hogue EX-01 - popular on BladeForums now, seems priced well for what you get
- Fox Predator 2 - Fox makes good stuff, check out Extrema Ratio, too
- Combat Elite RRF - ??