The AccuCases are plywood-style cases.
The Arriba bags are OK at best. They work, do a decent job for the money.
If it was me, I'd take the Design Spot 250 to a pro audio dealer and see if they can find a case or have a case made. You can even pick color and other nifty things(wheels/casters, latch types, corners, stackable.... whatever floats your boat.
I have a bunch of Arriba cases. Let me put it this way, they are far superior than using the boxes. All my boxes fell apart. But,since I have limited movement/movability in my truck and cases add weight, hard cases and my truck forlighting are not a match. Maybe later on, but not now. I suppose if I drop out my "hi-tech FX" fixtures and my Par38's, it might help, which I am planning on doing. I store my lights in the cab-over portion of the box on my truck.