I am going to have to stand up for World craft here. Out of all the map ed that I have tried, I can't say any of them trump WorldCraft.
I will admit that using it for Quake mapping is a pain, (converting texture to wad3 just to place them) but the fact that people go through all this just prove it does have something to offer.
It has by far the best UI and has the smallest learning curve that i have seen. less time learning a program, more time mapping

I will admit it is annoying that it is closed source, it would have been great if we could add features and enhance it but, sadly not.
Maybe an open source clone would be something to consider?