Dreamcast.
Unlike many failed platforms, the Dreamcast was genuinely fantastic and not just with rose tinted glasses.
It was stacked to the brim with arcade ports, not just the obvious like Crazy Taxi 1/2, Virtual Tennis, 18 Wheeler, Daytona etc from Sega but also stuff like Cannon Spike and Powerstone from Capcom. And 2D shooters galore like Mars Matrix, Gigawing, Gunbird. Fighters like SNK vs Capcom, Marvel vs Capcom, Soul Calibur, Guilty Gear X. And then there's games like Phantasy Star Online 1/2, Shenmue 1/2, Bangai-O, Chu Chu Rocket, Jet Set Radio, Space Channel 5, REZ, Sonic Adventure, Grandia, Skies of Arcadia..
For its short life the diverse list of unique and fantastic games is nothing short of incredible and it deserved so much more,