Soft sided, rigid bottom, zip shut Craftsman tool bag. Carries all my extra saw parts (rim sprockets, e-clips, fuel/oil caps, etc), wedges, 4lb hammer, extra chains, files, and assorted tools. Stays in the backseat of my pickup, behind the drivers seat, where I can easily access it for tailgate repairs. Rarely leaves the pickup. Also big enough to carry a set of chaps rolled up, and some spare gloves. All the pockets keep it organized..
I also have a dedicated tackle box type tool box just for my grinder sharpened chains. That stays within my pickups tool box in the bed. Holds about 25-30 sharpened 25” chains.. I throw the rocked chains on the floor of the pickup on the pass-side and when I get home they are placed in a box, to be sharpened later.
Another handy deal, is those metal clip boards with the storage under the writing surface. Used those all the time when I climbed. Hold important paperwork on top (client info, work orders, etc) and had enough room to store a complete Stihl tool kit rolled up in the tool bag you get when you buy a saw, plus a couple extra chains, files and handles, always had the bare minimum with me no matter what job I was on.