Well, just as a suggestion, since you're just getting into them, buying their newest, "Government Commissions" (a live album of sorts) would be a good start. It's not as cohesive as an actual full length, but it does have some of their best songs on it, especially the version of "Like Herod" which they stretched out an extra 7 minutes. As far as actual albums go, "Young Team" is generally considered their best. I myself started with "Rock Action". Really though, all of their albums are solid. Except for that remix album but I haven't given that as much time to as I should be.
But this is just one dude's opinion. Others on here might have some better suggestions.