Both classes are good. Vanguard/PT is one of the best DPS, its very easy to play. But you must remember one thing about vanguard/pt - it's a team class, you always running with the group, always in the center of action. As for shadow its probably the best solo class in this game. Its a best class for defending nodes/ sneak atacks/door capings. You must decide for yourself who you wana be.