It depends on what type of music you like. If you like older melodic death metal, The Jester Race is best. TJR is also softer than Lunar Strain, which you would hae to get with Subterranean,for the price of 1 CD. If you like heavier melodic death mixed with some lees melodic harder stuff, get Whoracle. If you like clean vocals and/or industrial music, get Reroute to Remain. If you like the older melodic death sound diluted a bit with new concepts and limited clean vocals, get Clayman. I can't really say much about Colony because I don't realy like it. If you want a lot of their great songs, in live CD, get The Tokyo Showdown. The problem with TTS is it isn't produced well for a live CD, and it is more a collection of their best stuff. It was recorded on the Cllayman world tour.
I would get Whoracle.
Steve