I don't think I need to post any examples as I trust people here are familiar enough with enough games on each system to have an idea. But feel free to post some examples if you want.
While I love the Dreamcast, I have to say it's the SEGA Saturn. It has so many great ones and the ability to listen to many of them on a CD player helps get a better idea. I not only love the music but the synth or whatever you call it sound of many CD-based games of that era. SEGA's first-party knocked it out of the park as usual for them but even getting to Shmup games, RPGs and stuff like Bulk Slash. Policenauts and Snatcher. It's honestly amazing. Grandia has one of the best themes for an RPG on top of its great OST. Panzer Dragoon's theme and music are just out of this world. I could go on forever.
I'd rank Genesis not far behind Saturn and Dreamcast 3rd and Master System last but not least. I'm one of the few that likes Master Systems sound more than NES despite growing up with an NES.