Melodyne is really cool. It takes your monophonic wave and plots it out on a piano roll. You can just grab syllables and move them around very dynamically. To my ears, there are less artifacts, and its very easy to use it to create complex harmonies.
The only drawback I could see is that it doesn't really do a realtime on the fly correction like antares can, but then again, even in antares, i usually used the graphical mode as opposed to automatic anyways.