[Root One Stop Shop]Roms, Kernels ect..

[Codegerm]

Or backup those apps from a stock ROM and reinstall them after flashing the custom.

Not really recommended bloat apps which reside in the system and preload partition. When going to a custom ROM, the Dev uses that space for the custom apps like different launchers and other enhancements. So space is a concern due to the limited nature of those areas. There is also the compatibility issue, some stock apps don't like AOSP ROMs.