Lots of stuff. I used to be all over "formula prog" like Dream Theater, Yes, Shadow Gallery, IQ, Symphony X, Spock's Beard, and others. I still like most of those bands to some degree, but with the exception of Transatlantic and The Flower Kings, they're not favorites anymore.
The first time I heard GYBE's "Lift Your Skinny Fists..." I was still in that prog phase, and so my reaction was like "What is this nonsense?" Somehow I actually managed to get that album before I even heard of the genre of post-rock, which is why the mp3s I ripped from the CD are still labeled as "prog-rock". Now it's my favorite album.