For portability when I need a small number of tools, sets are good (I only have one set of wrenches in a plastic case) but they sets also mean that some of the cost is for things that may never be used and those cases take up a lot of space. I have two Craftsman rolling cabinets, a SnapOn upper, several plastic Plano tool boxes and a Husky tool bag- the bag has what I need for doing a lot of the AV work without needing to make several trips to the van (and it's heavy enough) but I also have power tools that do stay in their cases because of the power cords, blades/bits, etc. The trick when using a cart or tool box is in how the tools are organized whether by the job, or type of tool. I have automotive specialty tools in one place, general use tools in their own drawers (screwdrivers, pliers, wire strippers/crimpers, sockets/extensions/ratchets in another and box/open end/combo and adjustable wrenches in another) and many other tools, but I have used them for different kinds of employment, so it's not the same as keeping everything at home & in their own permanent places. Then, there's all of my woodworking tools........