I'd say Quartz with Origami. Even though it's quite obscure, lacks solid documentation and the more custom stuff is not obvious to create, it's also more rewarding and once you grasp it you will be able to push yourself into unexplored territory like the Facebook Design team. The immediate visual feedback allows you to tweak everything to your liking with less chance of errors and going back and forward with the browser. It's not perfect by any means, my comps tend to look like spaghetti after a while and I dread having to deal with anything more complex than a single interaction per file.
I'd say Quartz with Origami. Even though it's quite obscure, lacks solid documentation and the more custom stuff is not obvious to create, it's also more rewarding and once you grasp it you will be able to push yourself into unexplored territory like the Facebook Design team. The immediate visual feedback allows you to tweak everything to your liking with less chance of errors and going back and forward with the browser. It's not perfect by any means, my comps tend to look like spaghetti after a while and I dread having to deal with anything more complex than a single interaction per file.