I've been buying "tactical" knives for a few years now,the last 2 or so being focused on more utility then tactical when it comes to blade shape and function. I've found that a blade designed for good utility/cutting tasks fits about every criteria I had for a blade for self defense.
The hands-down best tactical/utility knives I have come across have been the Carson M4 and M16. The m4 is the ultimate tactical design, IMHO. It comebines rock solid construction with excellent ergonomics and blade geometry. If you only want to own 1 tactical folder, this should be it. I've been carrying one for over 2 years now. No matter what new toys have come and gone through my collection since then, a Carson has never left my pocket.
JR