Nero without a doubt. It's much more comprehensive and better performing than WMP.
Nero 6 Ultra includes an app for just about everything and is well worth the $$. It will handle all your basic CD/DVD burning chores, (S)VCD, and backing up DVD videos. You name it, Nero 6 Ultra can do it
I voted for Nero even though i hate the stuff (NVE that is, unreliable and unstable as hell).. much better than the nonfunctional MS equivalent though. To do a proper/good job with DVDs it would probably be better to make use of a bunch of different tools, each good at their specific task