There is no best way, there is a best way for you
And only you can determine that
If you Bootcamp, you get the advantage of native speed, but you have to reboot
However, you can use your Bootcamp partition with Parallels or Fusion
If you run Parallels/Fusion you can run it at the same time as your OSX, copy/paste, etc
For me, there were no advantages to the headaches of a Bootcamp install, dual registration of Windows, rebooting, etc.
I chose to run Fusion and it is excellent for everything I do (MS Office, and some proprietary work stuffs)
If you game... Bootcamp
Most everything else (unless high end stuffs, Photoshop in Windows, or video editing), then virtual is usually enough