If you are auditioning equipment, the best tracks are those that you know extremely well. They need not have the best sound per se.

If you are interested in showing off your system to friends, Dark Side of the Moon is hard to beat for good sound.

Brothers in Arms by Dire Straits or Famous Blue Raincoat by Jennifer Warnes...boring but oh so good and predictable...Dark Side is a genuine classic and ignore this advice at you own risk..The Division Bell is almost as good but takes many hearings to get into the nuances...Joe Satriani 'Surfer' is one for the guitar...or maybe a massive dose of Malmsteen (any album!) if you want to turn the volume up...

Fragile- Yes or Big Generator-Yes, Graceland-Paul Simon,
Kashmir-Led Zep, Avalon-Roxy Music,