I wanted to know which is the best Tank Class to choose
Assuming you're willing to deal with whatever changes the expansion throws to your class (they're changing the tanks pretty heavily; making Guardians simpler and VGs more complex, modifying the importance and effect of Shield, etc.) and make your decision on what to play based on what is going to only be true for the next 1-2 months at most, the answer to "what is best for a new player to choose" is pretty much always going to be VG/PT: they are, by design, the simplest tank class to play and require the least knowledge and general skill to play effectively; Guard/Juggs have simple survivability but the most complex attack priority and resource management; Shad/Sins have simple damage/threat generation, but require the most knowledge and skill to attain acceptable levels of survivability.
As a self described "noob", you probably shouldn't try to complicate matters. VGs are super simple and easy to learn. Their priority is forgiving, their survivability is largely passive, and you don't need to research and/or learn about the relevant attack types of all of the various mechanics that will get thrown at you in the end game.