Dreamcast, easily. The most impressive system ever imho given it’s short lifespan.
Top games, in no order whatsoever:
Phantasy Star Online
Quake 3: Arena
NFL2k1
Skies of Arcadia
Power Stone 2
Honorable mentions:
Crazy Taxi
Metropolis Street Racer
Jet Set Radio
Virtua Tennis
Seaman
Game fucking sucks:
Shenmue