What is the best, most versitile program out there to make maps for games?

I've been mapping using Worldcraft for a game called Solitude for a while now, and I really like mapping. I would possibly like to get into mapping as a career. Worldcraft was made to map for Quake, and I'm pretty sure that modern games don't use that. I've heard that programs like 3D Studio Max is good, but I want to know for sure before I blow my money on a product that I can't use. Any suggestions? I'd probably be mapping for a FPS. I want to be able to come up to a company and say, "Here, I've got this map that I think would be perfect for you guys, and I can also do more for you if you hire me." so I want a program that would work with almost all engines. Thanks for your time!