A*Men, as it's still my favorite from the line and the most unique. After that, I guess it would be a toss-up between Malt, Havane and Cologne. Each of those 3 has, at some point in their development, a phase that I don't particularly care for, keeping them away from the top spot for me. I find the original almost flawless, however.
There's definitely a difference. For me, though, I'd have to go with Pure Malt. I'm not sure what it is with Pure Havane, but there's something about it that makes me nauseo