I know my choice seems controversial, but to me, the DC was a GAMER'S system. It was really like having an arcade on your TV. It was like a throwback to simpler times, with shumups, fighters and platformers galore!....yet with full blown RPG's, the 1st console MMORPG ever in life, sharp graphics and excellent presentation.....plus the hackers are STILL having a FIELD DAY with it! Plus, as usual for it being a Sega system, developers were bold and quite a few "niche" titles were released....games that would have never seen the light of day on any other console except a Nintendo one. New ideas were tested...some worked better then others, but at least they had the backing to get creative, rather than churn out the standard, lackluster sequel that was practically guaranteed to sell a mill.
The DC was a system built for gamers....HARDCORE gamers.....NOT their casual gaming cousins, and remote control holding parents and such. For THAT....for Sega having the bollocks to do what they wanted regardless of the status quo, cements the DC the best system ever....to me, at least.