i would continue using mp4 but with a twist. Implement the Auto Complete Recording feature. You can do it every 5 minutes, every 10 minutes, every xxx MB, etc. You can then use a joiner program to join the clips together with zero quality loss. And you get multiple benefits:
1) crash protection
2) easier to backup to cloud
2) easier to cutout unwanted parts or work with smaller chunks in editor.
4) less chance of corruption of one large file.
You can also use avi, but with this strategy why not use mp4 and get smaller file size?
I don't see any reason not to use auto-complete recording feature. You can always make 1 large file if you really needed it via lossless joining.