Some technical explanation is required for those under 35.
An analogue disc is pressed with grooves which are the physical wave-form of the content. One channel of a stereo record is vertical, the other horizontal. The needle is connected to coils in the cartridge, which produces the signal to be amplified. The disc is 12 inches in diameter and moves at 33 1/3 rpm. The first track is on a portion of the disc with a mean diameter of about 11.5 inches, the last track on a side is at a mean diameter of 5.5 inches. This means that the first track will have the capacity for a greater dynamic range and a higher signal to noise ratio, because the groove is moving twice as fast and has twice the effective bandwidth.
The ideal opening track is the most complex, with the most instrumentation and the greatest dynamic range. It should literally pin your ears back, in a way that is difficult to explain if all you have ever heard is compressed versions.
So my ultimate opening track is '21st Century Schizoid Man' by King Crimson. Not for any artistic merit, but because it uses the opening grooves to best effect.
http://www.youtube.com/v/-Iyj_Ze0BHA&rel=1The side 2 opener is similar of course, and all the contemplative acoustic stuff is towards the centre of the disc. All this makes no sense to the CD generation, as CDs read from the middle to the edge and have sufficient bandwidth to handle anything.
Damon.