I'm looking for a software to manage my pdfs with the following capabilities:

1. Organize into folders by topic, read/unread, etc.
2. Annotatation
3. Mac/iPad/iPhone platform
4. Can be used for citation management

So far I see two contenders: Mendeley and Papers - however Mendeley doesn't allow for (2) and (4) and although Papers does everything, I have to buy separate licenses for each device which is expensive and annoying.

Am I missing some other option?