i would say detroit is best for north america.

One reason why Pearson (YYZ) didn't get my vote for top airport was that it is not very user-friendly. At least that's how i feel.

i haven't been to too many other, overseas (non-N.A. airports) so i can't really comment too much; The toilet i used at Osaka (sp?) didn't work, or i couldn't get it to work.