I've found that the old, blue polypropelene stuff I have from college backpacking is still the best moisture mover as a base layer. This was a cheap $10 set from who knows where. It has shrunk a lot, so it probably shouldn't go in the dryer. My plan is to get a few cheap sets and rotate to avoid the odor they retain. I've also found that the wicking performance of a base layer is affected by the layer on top of it's ability to wick or absorb. Odd as it may sound, cotton does a great job of complimenting polypro. I still wouldn't use cotton in cold, but the principal is sound IMO.
I agree with Portis that avoiding sweat is priority 1, then the wicking ability of your base layer is less critical. I find the best way to avoid sweat is to reserve rain gear for conditions where precipitation is less desirable than prespiration. A soft shell layer makes this possible in most conditions.