Gens4Dreams Sounds Better in my Opinion after all it is for Dreamcast.
Overall I tested this bad boy Gens4All Emulator Package Gens4Dreams lol it runs so smooth just need to workout Button Mapping on my end probably. ABC - ABR , XYZ - XYL.
It is fricken awesome compared to that smashpack package to be fair I have not tryed but I seen a couple of videos to be sure it not being Emulated on Flycast/Redream etc and it was actually on real Hardware and it is awful terrible sound.