I use one of these in the kayak or bass boat. It's a beast but it holds tons, is bomb proof and has tons of room.
Made by Montana Fly Company (MFC). Easy to find online. I like having all of my flies out rather than in separate compartments.
For wading for bass, I use my CF design fly boxes (large waterproof boxes). I have 2.
One side is pretty deep to accommodate poppers and big deer hair flies. The other side I put slimmer bass flies in (streamers, crayfish, etc). They don't hold tons but between two of them I get enough variety in pattern and type for a day.
This link has a few big boxes you might consider along with the two I mentioned. The umpqua ultimate boat box looks promising for bass flies. It's kinda like the MFC box, but I'm sure it's not as expensive. The MFC is $60.