I'd say if you like Scream but not the later stuff, you're pretty likely to like Kaleidoscope and JuJu, but probably not much after that, even though neither is quite as raw as Scream. That pretty much covers their more agressive, guitar sounding stuff, along with the excellent Once Upon A Time: The Singles, a ten song collection of all their early singles.

This thread had me playing Once Upon A Time last night. It's one of the few really "essential" compilation albums from a band as it's got some stuff that I'm pretty sure never appeared on any of their albums...unless tacked on as bonus tracks like Hong Kong Garden or re-recorded with different arrangements and instrumentation for later albums.

Really, if I were making suggestions, which it appears I am, I'd suggest picking up Once Upon A Time (make sure you don't accidently grab Twice Upon A Time as it is their later stuff and you would hate it). If you're still digging that go for Kaleidoscope then JuJu. That's probably the path sticking closest to what you already like. After JuJu is when they totally went for their later, more synth-based sound...some of which I still like, but probably not what you're looking for.