You'll get lots of different opinions on that question...but here's my $0.02 worth:
Outpost Camp is nicer but Trail Camp is a lot closer to the summit, especially in altitude. Trail Camp has its own barren (read rugged and rocky) beauty rather than still being in the trees like you are at Outpost.
Personally, I'd rather put more miles and climbing behind me on the approach day and cut that time off the summit day. There are enough sandy spots to pitch a tent comfortably at Trail Camp so if you can sleep at 12,000', I'd say go on up there rather than stop at Outpost. That's what we did when Nathan and I did Whitney back in
2001 and I'd do the same the next time. (Actually, the next time, I'd like to try the Mountaineer's Route but back in '01, I figured it was a bit beyond Nathan's abilities at age 12. These days, he'd be leading me instead of the other way 'round, so we'd probably opt for the more challenging climb.)
As they say on the 'net...your mileage may vary...you'll hear good arguments for doing the opposite and staying at Outpost. Your choice...understand the tradeoffs and figure out which will work best for you.