My personal favourites for testing include...
Rush - Subdivisions (Signals, 1982) Nice warm tones from the synths combined with crisp notes on the drums
Golden Girls - Kinetic (Ministry Presents The General S'election, 2002) More warm tones but with added punch in the bass
Pink Floyd - Comfortably Numb (I shouldnt have to name the album for this!) Its awesome simple as.
Meshuggah - Pravus (Obzen, 2008 ) Chaotic!
Lamb of God - Laid to Rest & One Gun (Ashes of the Wake, 2004) Balls out Metal, love the sinking bass tones and big kicks at the end of One Gun.
Chicane - Far From The Maddening Crowds (1997) This is still in my top 10 fav albums of all time and is my number one test disc.
I tend to blitz through a lot of my favourite material as its the stuff I'm most used to hearing but these tracks are the ones that I usually go back to for repeats.