Submitted by MC Lordsson
I have used many different types, but found my favorite to be a Cold Steel Kobun. I would also like to recommend an M8. KBAR makes good knives as well which are combat tested better than any other manufacturer.
The Kobun by Cold Steel really fits most of my needs for a Combat/Utility knife. There is really only one thing wrong with it and that's the finish which is a bright, polished steel finish. As with any combat knife though, I would powder coat it after sharpening and before taking it with me anywhere. This tends to eliminate any rust, contamination, scratching, etc., and also takes care of any light reflection. Otherwise, this is a very light, very easy to handle blade with excellent killing properties. It has held up to some serious abuse through the years and I have yet to replace it.
Many call me a minimalist when it comes to knives because I prefer knife with no features other than a good blade and a great grip. I also prefer a Tanto. This may not be your type of knife, but for the work I've done, and continue to do, there has yet to be a good replacement.