Sugar Bowl is easier to get to drive-wise than Kirkwood, if that matters. Haven't been to Kirkwood (I'm a driving wimp) although plan to this season.
Sugar Bowl was our go-to mtn. last season. Judah Side of SB is fun and less crowded than the Mt. Lincoln side, good snow, good vibe, although on weekends, the whole mountain is overrun with ski-team/snowboard-team kids.
It would seem that either Sugar Bowl or Kirkwood > Northstar on a Saturday.