I use VMware myself, I use it to access my physical bootcamp partition without rebooting. It works well and I’ve never had any problems. It even has Unity mode so you can run Windows apps in their own windows right along with Mac apps. I’ve never used parallels, what is it you’re looking to do with them? They are best for light use, no gaming or anything heavy allowed, since they just emulate a graphics card more or less; VMware at least, I assume Parallels is similar.