I have been using VMWare Fusion myself. It isn't cheap (if price is an issue, try VirtualBox), but it works quite well, especially for Web browsing (I use a VM for all web browsing, so a browser-based compromise only hoses the VM until I restore it to a known safe snapshot.)
I recommend three things with Macs and virtualization:
1: If at all possible, buy a SSD. Even an external USB 3.0 SSD is useful with its diminished I/O. The main reason for this is that the bare metal OS and the VM guest OS are not fighting for the same physical drive head to do I/O.
2: VMWare doesn't have as many tricks in its arsenal to do memory swapping as it does in Windows or on ESXi... so max out the RAM. I would highly recommend getting 16 GB, minimum. 8GB will be cramped. 4GB... don't even bother.
3: A 2014 Mac Mini will have two cores, but with Intel's HT, you can use it as four vCPUs. I tend to just use two vCPUs as standard across all VMs unless there is a reason to do different.
As for operating systems, Linux and Windows run very well virtualized.
