Portable Tool Kit - what works best?

I have the same 3-drawer Craftsman toolbox, and also a cart like the one shown above, that I used to roll out to the driveway to work. Now I have a massive stack toolbox, so I just pull the tools I think I'll need and drop them on top of the cart (toolbox is in a small shop room at the back or my carport — the cars are in the carport). I also have a small Craftsman toolbox (with a tray) that is pre-loaded for road trips, and I might just use that for small jobs (does not include 1/2-inch sockets or torque wrenches). I have a heavy Craftsman tool bag, as well, that is also pre-loaded for road trips, for the other car – this is not as convenient because you pretty much have to dump it out to find anything. Then the British car has its own toolbox permanently in the trunk (guess why). You can tell I have a lot of duplicate tools... I also have a plumbing tool box and a small electrical tool box.