I think you should ask skals about UT mapping, since he does it at his College.
Source is pretty damn good with effects and everything, and mapping in it is similar to mapping in VHE 3.5, plus its very well made and doesnt have some of the annoying bugs in VHE 3.5.
For instance you can select stuff and if you accidentally click outside of the world (click the void) your selection wont get canceled.
Also players dont go trough the floor once you place em in the 3D screen, and other stuff.
I think you should try source and UT. Mess around with em, you'll find what you like
Also, have you ever mapped for Build engine? (Duke Nukem 3D was using it, very old)