What version do I buy?

I see I can buy starter edition which includes up to Underfoot for $19.99 or I can buy House of Thule for $39.99. I plan to play on the progression server and I doubt I will play for up to whenever House of Thule is open anyways but you never know. I guess my question is there any reason to buy anything but the Starter Edition if I just plan on playing on progression?

Also I can't see to find info on what RAF does for you? How much is the Xp bonus and does it do anything else for you?

:D

Darkpaw or Vulak?