Queensryche has had their fair share of turmoil over the years, in fact they're in the middle of a heated lawsuit as Geoff Tate was "fired" from the band he helped create.   They were one of the States more influential bands in the 80's.  They took a lot from Judas Priest and Iron Maiden, but by 1988 with "Operation Mindcrime" that had come into their own and created a masterpiece and one of the more well-known and ambitious concept albums of all time.  Here's one of the videos from that release.

The legacy of Queensryche has remained alive in many bands around the world.  Perhaps one of the biggest is the international act Kamelot who continue to put out powerful Progressive Metal.