Dreamcast by a country mile. Sonic Adventure 1 and 2, Crazy Taxi, Chu Chu Rocket, Virtua Tennis, Grandia 2, Powerstone 2, all those lightgun games.. So many often overlooked gems..
Xbox has the best online going for it NOW but back in the day it was still in its infancy. So all the og Xbox really had going for it was Halo and Morrowind (and a particularly giant controller). It didn't even have Rareware, Dead Rising, or Gears yet.. Once Sega went to pasture on the hardware front though, I did jump on the Xbox with the 360, and still enjoy the XB One/Series X. Though I wish Sega would make a comeback console :/
"We hold these truths to be self-evident - all men and women created by the, go-you know.. you know the thing!" - Joe Biden