I have been using QubesOS for a while now, I am happy to see it got a mention. Before using qubesOS, I had a vmware VM with a browser.
I believe using Qubes is a bit more secure than an OS with a hypervisor running another OS with a browser though.
See:
http://theinvisiblethings.blogspot.com/2012/09/how-is-qubes-...
Or:
http://invisiblethingslab.com/resources/2014/Software_compar...