I was a long-time Roxio user, and switched to Nero a couple of years ago. Never looked back; they bundle lots of good stuff with the burning software and seem to pay attention to bug reports with regular updates. Email technical support actually responds to you, as well.

Nero seems to give you a lot more in the way of things to tweak; overall more control over your ripping/authoring/burning experience, and Roxio (at least in earlier versions) tended to dumb things down. I'd rather have too much control than too little.

Since you're already a Nero user, it'll be cheaper to upgrade to the latest version than buy Roxio outright. Even if the prices were identical, I think you get better support from Ahead (Nero).