Got to go with the crowd here and deffinatly say ASE.
1. The pings seem better
2.The filter system is better
3.If server is full,it holds a place in line till a spot becomes available
4.No more bullshit chat in the gamespy lobby to tolerate!
5.For me,when I came out of a game in GSA it used to hang for an eternity,with ASE it doesn't.