The Sentinels dps is far greater than the Guardians just because dps is the only thing a Sentinel can do...from my own experience when it comes to the story quests it may become difficult at times to solo while playing as a Sentinel because we're sorta squishy, you could always have T7 tank but if you're a fan of Kira like me than tanking tough story bosses can cause a bit of nerd rage and thousands of credits spent on stims and medpacs. If your looking for a hardcore dps class with excellent raid buffs than go Sentinel. If you want amazing tanking abilities and more flexibility in your class than go Guardian.