Trooper Vanguard vs Jedi Guardian

So typically in MMO's, I am usually drawn to the heavy armor classes.  I primarily played a Resto Shaman in my WoW days, and while it's not really a heavy armor class, the fact that they could use a shield helped offset that.  I did also play as a Ret Paladin for some time, mainly to do 2's with my usual PvP partner as Rogue and Ret.  So that being said, I've been playing the Jedi Guardian, Trooper Commando and Vanguard for a while now trying to decide what to play post release.