I prefer using VMWare, But If you want to pay I would recommend VMWare otherwise go VirtualBox (Freeware).
I do like VMWare because it has a lot more features with Guest Support, But yeah the choice is up to you.
If you are running Windows 7 or Vista, You may be able to use Virtual PC. But that isn't supported with Windows 8 and every Operating System after that.
no doubt that the virtual box of oracle is free and works very well and light. it virtualized many things with it and it works perfect has options to export and import virtual machines.es the best then if it could be used
VMware Workstation 12.5 Pro is very good but it is paid.
VMware, cuz i still have a license from my previous company.
VirtualBox, cuy it's free.
Docker, is not really a VM but i started to see why people like this kind of container thing so much. So I'm currently trying to get into this
I used to use VMWare but moved over to VirtualBox when it was launched as it was free, I also find it is less resource intensive than VMWare was, you can clone machines and I have run everything from Windows XP, 7, 10 to MacOSX, I use it for Kali tutorials while I learn new skills, I have set it up in my classroom so students can try out different operating systems without breaking their computers.