PS3 and 360 are good candidates, since the Wii did nothing for me. But I didn't really enjoy the 360 or PS3 that much either.
N64 and Sega Saturn were fine systems, but didn't leave a lasting impression on me aside from a few gems.
So that leaves the OG Xbox and Gamecube. The OG Xbox was a great system that differentiated from the PS2 substantially. It had great 1st party exclusives and great 3rd party exclusives. The only reasons I gave the 360 a chance was due to how good the OG Xbox was, and how cheap I got it for. ($50) The Gamecube was also great, with a few gems, but again it needed just a little bit more. So the winner is OG Xbox.
Of course you might say I am forgetting the other generations, but for the most part the winner held 90%+ of my attention.