there's an interesting parallel between Epicureanism's concept of ataraxia and Buddhism's nirvana. they can both be described as non-reactive states of mind; absolute immovable serenity is an aspect of both.
that said, i don't mean to equivocate the two beyond that particular point. i will admit i am biased towards Buddhism, but Epicureanism's goal of aponia — freedom from physical pain — seems like an impossible goal to me. (one could argue that ataraxia is too, but to me aponia is most certainly unattainable because, well, shit happens and you'll get hurt sometime.)
anyway, all this is to say that both Buddhism and Epicureanism have ambitious goals. whether one is better than the other is a thorny question at best; but to me at least, Buddhism is more approachable