Crankbrothers M17. Have one for every bike. Spoke wrench, emergency chain tool, allen keys, torx bit for rotors and even a crappy but effective selection of emergency open end wrenches.
Like someone said many times is it me working on other people's bikes. Bit of hubris to think even a well maintained bike won't need a fix or some sort of adjustment on the road every now and then. Especially when riding for days.