Though it's a good album, I would say definitely NOT purgatory afterglow in the context of this question. Plenty of time for that one later.
Though it's not the best of those you've mentioned, I'd go with Crimson first. It's very catchy and shows off a lot of Dan's different talents. I can't even recall which album I heard first from Dan, but Crimson was something I heard very early on and it's the album that made me go out and buy many of his other cd's.