I personally wouldn't buy the lightweight (plastic) manix 2 with the BD-1 blade. Given the choice between the two you're looking at, I'd take the Para 2.
EDIT: A lot of you folks seem to think the OP is trying to decide between the standard Manix 2 and the standard Para 2. He's talking about the Lightweight Manix 2 with the BD-1 blade. The Para 2 in this case is the heavier knife.
Now, if it were a choice between the 154cm Manix 2 or even a sprint run M2 and the Para 2, I'd have a hell of a hard time choosing between the two. In the end I'd probably go with the Manix 2, but they're both equally awesome knives IMHO.