I don't know if it meets but your needs, but I love PasswordMaker (http://passwordmaker.org). There is no need for sync'ing, because the password is generated from a master password and configureable per-site data (by default, the web-site address; but you can add more data sources if you don't like that). It has an extension for Firefox that auto-completes passwords (configureably, remembering the master password per session so that you don't ever have to type it); there are widgets for Windows and Mac OS; there are Android and iOS apps; and, always, there is the fallback web page, which you can use anywhere that you have a web browser.
EDIT: Since I am trying to indulge in quite a bit of advocacy here, I want to make it clear that I am in no way affiliated with the project. I just stumbled on it a long time ago, and have been delighted with the way that it fills my needs.