@jcdeboever Stayed with it becaused of several business applications. My son seems to think they will run on a virtual windows box inside Mac but hasn't had time to check it out. Would really like to dump MS
I'm a mac user but I use a LOT of virtual machines... in part because I have to run software demos (on different operating systems... mostly Linux) as well as some astronomy software where device support for some astronomy products is only available for Windows.
I've run these using:
1) Parallels
2) Virtual Box
3) VMware Fusion
In the astronomy world, Windows is by far the most popular platform. There are a few products I use where the only software support is on Windows and that's why I use VM's.
In the photography community it's much different... I have yet to find anything I would ever want to use where there isn't either (a) a Mac version of the program and the Windows/Mac versions are on par... or (b) there isn't an alternative program that does the same thing (even if it's different software or by a different company) that fulfills the same need and it's at least as good if not better.
In other words, if the only software I were using was photography software, there would be no need for a VM.
Parallels
Parallels is the most popular virtual machine on the Mac primarily because they were the first to offer a VM product that ran on that platform. I ran Parallels for years ... I no longer recommend them and they are actually the only VM hyper-visor product that I actually suggest people avoid. I found that their implementation and especially their installs were a bit on the clunky side. On a Mac, most applications are packaged so that everything the application uses is in a single directory and can neatly be upgraded or uninstalled. Parallels doesn't work like that... it scatters files in folders all over the hard drive. You must use their tools to upgrade or uninstall the program. Trouble for me started when I upgraded my OS, then tried to upgrade Parallels... but the upgrade failed. It failed because the developers had hard-coded some OS version dependencies that caused the installer to fail because I wasn't running exactly the same OS version (their script assumed an out-of-date OS and my OS was up-to-date). I contacted them for help (they used to be great ... but as their company got bigger the support got much worse) and they basically told me I was out of luck.
As I am a technical person with about 30 years in the computer industry I asked them to just send me a list of files that I need to remove and I'll take care of it myself. They refused. I finally found a post on the Internet with other equally-frustrated users who chased down every file and posted the full list. It took me a while to find and eliminate them... but I did it.
This finally put me in a position where I could upgrade my Parallels version. But after that sour experience I was so off-put that there was no way I was going to expose myself to more abuse... so I moved on to...
Virtual Box
Virtual Box is actually free and open-source. It works extremely well. I found it follows the Mac's model for how software should be installed (everything is one folder with the exception of a couple of drivers but those drivers are actually in the folder Apple suggests for 3rd party drivers). It's very easy to install, un-install, upgrade, etc. It's easy to use. What's not to like?
While I am generally positive about Virtual Box, there are two caveats.
1) I found that when I benchmark the performance of software running under Virtual Box (often people will just abbreviate as "VBox") I found that running the same OS and software under VMware Fusion had slightly faster performance (maybe 10% - not a huge difference but enough to be noticeable.)
2) This is a bigger caveat... this one pertains to how Virtual Box handles physical USB devices. If you install a physical device on your computer, you have the option of assigning that device either to the host OS (in this case the Mac) or to the "guest" OS (e.g. the Windows OS running under Virtual Box -- all VM hypervisors allow this). Virtual Box's implementation is a big sluggish and it actually created performance problems for some of my devices -- which didn't quite work correctly.
If you're using Virtual Box to run a guest OS where the applications aren't dealing with physical hardware (USB devices) then I'd suggest using Virtual Box. If you are using physical devices then you might want to consider....
VMware Fusion
VMware is basically the 800lb gorilla of the virtual machine hypervisor market. VMware Fusion is the name of their Mac version. I switched to VMware (and this is what I still use today) because I needed to work-around the performance issues that I sometimes had with Virtual Box and also because there's no way I was going to re-install Parallels (my short write-up on Parallels doesn't accurately describe how much pain I went through trying to solve the problems they created.)
I find it's fast/snappy, I have yet to find any hardware device (mostly USB devices) that it can't connect to the guest OS and control, and also like Virtual Box it has a clean install/update/uninstall and doesn't scatter or modify files all over your filesystems.
It's not free but it is good and worth the price.
Lastly... keep in mind that while the virtual machine software (sometimes called the "hypervisor") allows you to run lots of different guest operating systems, the VM software doesn't include the licenses... this means that suppose you buy VMware... you still have to purchase the Windows software license from Microsoft.
One major advantage of running on VM's is the ability to "snapshot" the VM image. Basically the VM creates a huge file on your host OS's hard drive which represents the hard drive of the "guest" OS. The snapshot basically freezes that file and creates a 2nd file which only has the changes that have been made since the snapshot was created. It doesn't take as much disk space as having to copy the whole hard drive since it can just get any unchanged files on the original "frozen" snapshot. But the real benefit comes when you want to do a roll-back. So when you're regretting having updated the OS because it's now broken a bunch of stuff that used to work, you tell the VM software to revert back to the snapshot state and it will be as if you never installed the update.
Whenever I do any major updates... I tell the VM to create a snapshot before I start. Then I do the update... I run with it for a while (possibly even many weeks) to make sure I'm not having any issues. If I think it's safe, then I'll delete the "snapshot" (that causes it to merge the changes into the main image). You can have snapshots on top of snapshots on top of more snapshots.