what is more valuable?

[illumanat'i]

in my limited experience they are equally important...

keep in mind there are 29 boxes on the top of the ramp and you get 25 points for being on top, so given that you never get all the boxes on the top, and the tall stacks never stay stacked, you have a good chance of getting 13 boxes with a stack of 2, or 26 points

so being able to get to the top first is important, because without those boxes you've pretty much already lost, and being able to stay on top at the end is important, because without the 25 or 50 points most teams normally lose (i know, my team lost because the refs decided we weren't fully on top, something i disagree with to the third degree)