The following presupposes that you are indeed one of the good guys. If you are not, I hope you choke...or run into me in some dark alley...
For a stun gun to be effective it must be in contact with the...er...subject. That means that you're going to have to grab him with one hand and apply the stun gun with the other. That means you have to be close. If you can touch them, they can touch (punch, kick, STAB!) you!
Nope, stun guns just don't work very well. (I've taken a shot in the ribs from a 100,000V one and all it did was make me mad.) The cartridge type Taser seems to work fairly well, but more importantly it can be deployed from a distance. That is what I'd recommend, if you must use electricity.
The OC spray or stream, from Fox Labs, is the best of the pepper sprays that I've used. (By "used", I mean that I have been sprayed more times than I can remember with most of the stuff on the market. Fox introduced me to a whole new level of pain!)
But be advised that it is not instantly incapacitating. It can take up to several seconds for the subject to "feel the burn" and he can injure/kill you if you just squirt him and stand there waiting for him to fall. Use that time to employ what M. Otter so elegantly calls the "Nike Defense". Then call the cops and report that you were assaulted. If you just run off and the bad guy/s report YOU, guess who the cops will probably believe?
Ken Cox said:
...I no longer have the will to mutilate another human being with a gun or a knife, even in self-defense...
I respect you for that statement and it is with true brotherly love for you that I say, "You must move to a monastery...NOW!" If you will not protect your own life then you must go to a place where you can pray, in safety, for those of us who will.
Bob