The Kings and Sonics were in Sacramento and Seattle at the same time for 23 seasons. In those 23 seasons:
-Sacramento drew more fans in 20 of them.
-Sacramento has seven top-10 seasons in attendance. Seattle had zero.
-Sacramento was in the bottom half of the league in attendance six times. Seattle *wasn't* in the bottom half three times.
All that despite the fact that in those 23 seasons, the Sonics were unquestionably more successful. They made the playoffs 14 times (9 for the Kings). They advanced to the second round or better 9 times. They won 60-plus games three-times (attendance in those seasons: 15th of 29, 15th of 29, 20th of 27). They went to the Finals.
Arena seating capacities:1985-88: Seattle 14,252, Sacramento 10,333
1988-94: Sacramento 17,317, Seattle 14,252
1994-95: Seattle 19,000, Sacramento 17,317 (Seattle played at Tacoma Dome)
1995-2008: Sacramento 17,317, Seattle 17,100
So, for 19 of those 23 seasons, Sacramento had a bigger arena.