I've been to Liverpool, Altamont and Hunter Mountain numerous times. Cortland once.

Cortland has a pretty weak festival, but the concert at the end is awesome. The rest are all great. I prefer Liverpool to Altamont for games, just because Longbranch Park is so much more pleasant than the dusty fairgrounds in Altamont.

You excluded one of my favorites, the East Durham Irish Festival, held every year on Memorial Day weekend. http://www.east-durham.org/memfestival/index.htm