I've always found performance and stability to be quite lacking with vbox. Parallels and VMWare are both mature, performant, frequently updated, and well-supported, so I see little reason not to use one of those, especially given that I'm using it for work and don't want to wait on a VM for no good reason.
On the other hand, Parallels and VMWare frequently charge for their updates. I rarely find software that has such short license spans. I bought Fusion 5.0.3 in June and they already want to charge me for Fusion 6 (btw. the only version that officially supports Mavericks). Fusion 5 is now dead in the water.
This is okay for me on a single machine, but at scale of a development team, it gets expensive quick.
