There are so many knives out there that would work excellently in a self defense situation. Emerson knives are specifically made for self defense. Though they are quite expensive and most are weak when it comes to everyday tasks. A waved knife, in my opinion, is faster than any assisted/auto knife out there, as it has a small lip on the blade that catches on the corner of the pants which allows it to open as you bring it out. Emerson and Spyderco both have waved knives in production. Check out the Spyderco Delica or Endura with the wave feature. Kershaw also makes many tough knives at affordable prices. Check out the Kershaw Blur. Assisted open, fairly good steel, and a solid lockup. If you give me more information such as price range, preferred blade length, ect, I can narrow it down much more for you.