I use the Lifesystems mountain-type kits as a basis and then add/remove to suit my preferences/circumstances.
In the UK, I keep a big one in the truck, a medium one under the seat of the quad, and a little pocket one for stalking.
In Africa, I have a big one in my bag, with the addition of a separate sterile kit which the staff know to hand to the doctor so he doesn't stick me with any dirty needles. This latter has been used once and I was very glad of it, as I lay delirious in a pool of other people's p1ss and vomit in a delightful little clinic in Catandica...