Is NullDC better or worse than DEmul?
I've got them both, I just don't know which one I should be messing with more. New(ish) to Dreamcast emulation.
they are two different things. Naomi was an arcade system based of the Dreamcast hardware and some naomi arcade games were made for the dreamcast home console as well
Nulldc is for Dreamcast games (isos) and is a very nice emulator. Compatibility is very high and it can upconvert the games to 1080p
Demul is for Naomi arcade roms (Compatibility is high
IF you have powerful pc/gpu but, the emulator itself is buggy)
Side note: Nulldc does have naomi emulator but its not very good and demul can play dreamcast but, its not very good either.