Well from what I know, you will not compete in PvP unless you dish out all your funds in the cash shop...? So eh... I would choose FW over PWI! I am not sure how endgame pvp and what not is, but I like classes/world of FW much better. As far as differences, I feel they are the same game with different skins. Whatever you find more pleasing :P

And you may as well skip f2p and look at Aion if you have not. Open pvp and flying pvp! Yes, you get wings to fly with and fight in the sky with in the abyss. And 4.0 will be released next year with 3 new classes! WOO! It is p2p quality but completely f2p.