The new one (Addicted) is pretty good. I really liked Synchestra or Accelerated Evolution. Infinity had some really good tracks as well. Let's just face it. Anything that man does is "golden" to my ears. All SYL for that matter also.
I think that Accelerated Evolution and Addicted! are the easiest ones to get into. Maybe those would be great to start with. For me the Ocean Machine is the best. It will never leave my 512mb Creative Muvo mp3 player..
From SYL I definitely prefer the City record. Awesome chaotic atmosphere in it.
Listen to Ocean machine first, that was my first encounter with the god that is devin and it is still my favourite. Then check out Accelerated Evolution, and to see where he started experimenting with stuff check out Infinity its a great album to show you how some of the later albums got their influence.
also check out the song Deep Peace on "Terria" from 2:43 onwards is one of my favourite sections in a song ever.AMAZING
if you buy Accelerated Evolution get the version with the dvd. That will show you a good range of catalogue.