Armadillo All Condition 25's when commuting on my cross bike. The all conditions are the closest to a slick.
I used to use Armadillo Nimbus 28's but new rims necessitated a narrower tire.

Heres an interesting link, of a test of a few tires. Too bad they picked crappy tires to compare to the dillo's. I'd have liked to have seen a dillo vs gator vs schwalbe

http://biomech.me.unr.edu/wang/abstracts/puncture.htm