I do not face the same quandary with a pocket knife. I always have either a Spyderco Tenacious or Persistence on me. (Depending on local laws and wardrobe requirements) Size and quality criteria are easily met with the tenacious/persistence. The kicker is they cost ~$45 so I don't have to worry about losing them and I never feel guilty abusing them if I need to scrape or pry something. The cherry on top is that I can throw a zip tie on the thumbhole and I essentially have an auto opener that is legal where actual auto-opener would not be.
I tend not to lose things when actually wearing them; it's when they go into storage that it becomes a problem, and I've solved that with labeled/inventoried plastic bins and baggies. So, I didn't really care about cost (maybe $100?). I got Fenixes when slickdeals said Amazon/etc. had them on sale (some around $10), and I got some other stuff from PXes in Iraq and Afghanistan (where it was also cheap -- like the Cold Steel SRK was $49, so I got a bunch).
(on the other; I don't have a California CCW because I don't live in San Mateo County (the only Bay Area county which is vaguely lawful in how it issues CCWs); for states where I can, Ruger LCR or G19 depending on clothing, rarely a 1911. If I move to San Mateo, probably Sig P938.)
The only lights I've been amazingly impressed by are the Surefire shotgun foreends I put on my Mossberg 590s, and the kickstarter programmable rechargeable light (hexbright).
For a knife, I most often carry a Kershaw Cryo or a Ken Onion Ripple. I have no illusion about using either for self defense.
See this page: http://www.nononsenseselfdefense.com/knifelies.html
A lot of that applies to guns as well.
The very specific case of someone grabbing a gun is the one area where I feel comfortable using a knife in self defense. Other than that it would be my absolute last choice (unarmed, even, might be better).
I'm generally in my house, in my car, or in an office somewhere -- all fairly secure environments, where I have 10-15 seconds to draw, or possibly even grab a long arm. My goal is to have a house/office on enough land that it takes >60sec for even SWAT to get to the front door after initially being noticed (a 150mph helicopter might be difficult, though), and maybe 30+ seconds to breach it (minimum).
Without a non-lethal option, you're stuck. There are situations which don't warrant a lethal response, or which don't absolutely require a lethal response, but where if you get close, weapon retention becomes a serious issue, turning the whole thing into a lethal force justified encounter. Which is a huge problem for police who open carry handguns; less of an issue if you CCW.
Tasers are huge, and unless openly carried or in a house, are basically the same form factor as a handgun. If I were a high-risk person (smaller, female, disabled, etc.) in a place where I couldn't or wouldn't carry a handgun, it would be an option. It might also be an option in a place where use of force but non-lethal force was likely, like a mental hospital, bar, etc. Otherwise, the optimum seems to be OC/knife/light, and then handgun.