For free (I, too, was tired of the 'subscription model' annual upgrade pleas/threats), I really have to try to find a problem with it. Parallels seems to virtualize Mac OS more smoothly.

It works well with most Linuxes I throw at it (have had some issues with Linux Mint and video drivers). I triple boot on my MacBook, but may toss that for using virtualized PCs. Two-way clipboard support just works, and the granular control over the emulated hardware (how many cores, how much RAM, what size drive, etc.) makes it sweet for testing system parameters.

It's not quite as nice to configure as Parallels, but once it's running it's fantastic. What can be said has mostly been said, but I'll chime in.