I have been a corrections officer for nigh on 10 years now and our primary weapons are all less lethal weapons, notice the term LESS not NON. I am certified as a Taser instructor, an OC instructor, impact weapons instructor, defensive tactics instructor, Pepperball instructor and armorer, and an edged weapons defense instructor. I personally designed, wrote and regularly teach the training curriculums in all of the above areas. Given all of that, I can say, and this isn't to enflame anyone but a lot of what has been written here is very good advice and some of it is...um...let's say, less than accurate.
1) Something is always better than nothing.
2) OC spray IS effective when the right strength is applied properly. All of our officers carry First Defense .7% and I have yet to see someone who was unaffected by it. If you want a more effective spray buy a formulation that is an OC (pepper) and CS (tear gas) blend. CS sprays are not legal everywhere so check this out where you live first. Always buy a liquid stream, foggers are only good for crowd control. You should always target the face with a spray but an OC/CS blend spray will cause coughing, choking and tearing even if facial contact is not made. Whatever you buy practice with it and I HIGHLY recommend having someone spray you with whatever you are going to carry and practice making an escape or fighting while you are disabled so you know what to expect when it gets on you. Buy a name brand, Sabre Red, First Defense and Fox Labs are the best out there. NEVER buy the cheap crap they sell at the register at big box stores.
3) The civilian Taser models, C2 or X26c work very well when properly deployed but they are dependent on a solid large muscle mass area hit to cause incapacitation. The good thing about these items is if you successfully hit with them the timer on the device runs for a full 30 seconds. This is intended to give you a sufficient window of time in which to escape. Fire, drop and run. Then if you send the police report to Taser International they will replace your unit for free. As far as Tasers killing people, I have been tased somewhere around 10 times in various training courses over the years by 3 different models of Taser weapon and I am still alive. Not only that but I have tased or been present at the tasing of many people, both LAWE types and criminal types over the years, and they are all still alive as well.
3) The Pepperball Flash launcher sucks. It's heavy, cumbersome and extremely hard to fire, I had ot use two hands to make it work. However, the Pepperball keychain unit is VERY effective. It's small, light, easy to carry while running and it discharges a massive amount of OC powder, right around 34 grams, more than 3 times the amount in a Flashlauncher ball. The powdered OC is great becasue it disperses and contaminates a large area but is still projected well away from you. It also sticks to skin, gets in eyes, noses, mouths and lungs and it burns as bad as or worse than any of the liquids I have been sprayed with, which is up to 5 now.
4) Impact weapons are not legal in all states and require much closer contact to effectively deploy and as such should be avoided unless as a back up. The best way to defend an attack is to keep the person as far away as possible or to use the weapon you have to create a window for escape. Even if grabbed from behind it is much easier to deploy a spray or a projectile based weapon over you shoulder than it is to successfully deploy a striking weapon.
5) TRAINING, TRAINING, TRAINING! Whatever you buy practice, practice, practice! You should be able draw, and operate whatever wepaon you carry in the dark, after being exposed to it yourself, in the rain, whatever.
Sorry, couldn't help but throwing in my 2 cents, I'll climb down from my soap box now. Y'all have a good day and stay safe.