That depends on who you ask.
I rather the dualboot method, because its simple and solves A LOT of bugs and possible problems.

However, virtualization does have its advantages.
One being that you do not have to shut down the PC and reboot to the alternative, so it makes working quicker.

I should mention that I have to use Windows *gulp* Vista at work. And then have to use virtualization in Vista, to use Windows XP. Crazy I know. I mean they have IBM laptops with square (and red) displays. Do you guys even remember BenQ.... yeah there is one of those desktops there. And the IT guy that works here manages our on-site servers for the whole country, he's toting around a Surface Pro 3. He hates Macs, and doesn't understand Linux. And I have to suffer. There's heaps of ways to the computers could be hacked (cause they're older then my underwear) but no-one really cares. I don't think a hacker would care either, cause the whole system is so "bleh".