The most important thing is to understand yourself. Most of us don't get flat tires very often but, when you do, it can be aggravating. If you're the kind of person who gets upset easily, you want the quickest and most convenient inflation system you can find. If you're a more laid back kind of person, the time it takes to reinflate your tire isn't as significant.

CO2 is, by far, the speed and convenience king. I don't live in goat head country so I don't get a lot of flats but, when I do, I hate it. For years I only carried CO2 in my road bike saddle bag and never had to walk home or beg a pump from another rider. I would recommend practicing at home at least once. I also always took the time to check my tire and tube seating before shooting in the CO2. I never had a misfire. If I was still riding my road bike, I'd still be carrying CO2.

That leaves pumps. The laws of physics can't be violated no matter who makes the pump. There's 2 factors to consider, pressure and volume. Skinny pumps let you achieve higher pressure, pumps that are long and/or fat build up volume more quickly. I like relatively big pumps because I want to get back riding as quickly as possible. Dinky little mini-pumps may look cool and fit neatly in your saddle bag but, if you actually have to use one, they suck. If the pump connects directly to the tire without a flexible hose, there's also a technique factor to consider or you might tear your new inner tube at the base of the valve stem.

For the record, I stopped using CO2 when I switched to recumbents because one 15 gram cartridge will only inflate my tires to my minimum get-me-home air pressure. Now I carry a Topeak Morph pump. It works like a mini floor pump. The only things I don't like about it are that I have to bend over more than I like to use it and I think it's ugly.