My experience with Buddhism and Stoicism has been the opposite of yours. I find Stoicism to be a vague collection of rules that's hard to detangle and full of legalisms and exceptions. I don't see the underlying principles as clearly as I do with Buddhism.

While I agree that Buddhism has many descriptions of virtuous and non-virtuous mental states, these are all grounded in a few simple principles. In fact, I find one underlying principle behind all of Buddhist ethics: all your bad behavior is caused by your selfish motivations. Tibetan Buddhism calls this self-cherishing. It's rooted in self-grasping, which is clinging to the intuition that you exist intrinsically, possessing an immutable soul.

If you exchange yourself with others and act in the best interest of others instead of acting in your selfish interest, your behavior will naturally be virtuous, and you will be happier. The "rules" and precepts all spring from this simple concept. It's basically the golden rule of Buddhism. When you see the underlying order, you don't get caught up in whether or not you are following some rule. You know when you are acting out of self-cherishing and when you are not. It's simple and powerful. And it's not open to rationalizations and legalistic rule interpretations.

Particularly in Tibetan Buddhism, the meditations are emotive. You think about certain concepts and work with the emotions that arise. This emotional training aligns your emotions with virtue so that the Eightfold Path becomes a natural path to follow. You follow the path because your emotions align you with it, not because you need to follow some set of rules.