All the classes you have are the totally fine for pvp as it stands now. Juggernaut in range tree, vanguard/powertech in assault/pyro, shadows have quite a few builds but better ask on a separate thread for advice or have a look as they will be definitely thread as such. On the new classes you mention operative healers are unkillable on the hands of an experienced good player but dps wise only exceptions excel. Snipers are pretty good and in my opinion well balanced. Maras are the fotm class for months now. Commandos is a no go for pvp. But this the current state of the classes and many things might change with 1.7. So the question is do you want to pvp sub 50 or 50 level? If you never prod before you will start at a gear disadvantage at 50 but with the recent changes it is very quick to gear up. So don't get disappointed in the beginning.
Cool, thanks for the advice. I'm half tempted to level a Commando just because they suck now. By the time I get to 50 I could hope that it will change.