What do you use? Frame fitting full length? Ultralight micro pump? CO2? Which is the best option for any specific purpose, for example commuting, proper MTBing, touring etc.

Currently I use picrel, I chose it because it seems to be fairly good at everything, durable, light enough, it manages to get my tyres up to 70 psi without too much trouble and it has a built in pressure gauge.

I'm planning a few tours and was thinking about whether CO2 might be better in terms of weight and space savings,