About the best I've foudn for my uses are the Keter range. They have many different types including a sort of stackable thing they call the "MasterCart". The basic toolbox is pretty decent and it's strong enough to use as a temporary support for cutting timber. The arrangement with internal trays, dividers and external drawers seems to work well.
Find them can be PITA. B&Q used to do them but seem to have swapped to own brand. Most of the ones I see now are sold on eBay. They are fairly popular in the USA.