A strip of 'rat tails' is cheap and what I carry, had to use it once and was well worth it.
Sadly it was on a brand new tyre and after a couple of months it started to leak slowly. Took it to the tyre repair place and the hole was too near the sidewall for them to repair, so new tyre needed. However, the repair I did took 10 minutes at the side of the road at night, which is a lot quicker and more convenient than waiting for the AA which are averaging 6 hours on each of the two call out's I've needed, plus I got an extra couple of thousand miles out of the tyre.
I'm not a fan of CO2 canisters, great for a bicycle but not so much for a motorbike. If you use it and find it's not enough, or a canister fails, you're stuffed. I got a small 12v air pump from Wilkinson (supermarket) for £10 and put a bmw style plug on it. when needed I just start the bike, plug in the pump to the accessory socket and in a few minutes you're up and running. It was even powerful enough to seat the bead on the front tyre when I changed them a while ago, not quite enough for the rear but then I could probably have used more tyre soap.
All in all, a cheap and effective solution. I know several people on here like the Stop 'n' Go tyre plugger kits, but when I did some searching online I found a lot of negative reports of them not working so I chose to go with rat tails which seemed to have a high success rate. It's the old 'you pays your money' choice.