The Benchmade serrations are kind of reverse from the Spyderco serrations: sharp valleys and rounded points on the Benchmades. The disadvantage is that the Benchmade serrations are less aggressive in cutting. The advantage is that they're less vulnerable to getting the tips chipped off. I've chipped off the tips of just about every kind of serrations, but Spydercos are usually the first to go.
Which you'll choose will depend on what you're going for. I personally would rather have the more aggressive serrations. I don't like partially-serrated blades, and don't find all that much use for fully-serrated blades. But when I do bother to carry a fully-serrated blade along with my plain one, I'm typically going for the most aggressive cutting possible. On the other hand, if you care about the aesthetics of broken points, or are cutting into things that break off the teeth easily, Benchmades serrations are the way to go.
Joe