Another post about Reference Managers for Mac OS X - Mendeley, EndNote, Zotero

I know this has been posted in the past but as these programs are constantly evolving, I felt that obtaining your up to date opinion is of value.

I have been using Mendeley happily for over a year. Occasionally there are hiccups with the word plugin, and the recent 64 bit update to Microsoft Word rendered it non-functional again. Given the unstable nature of Mendeley's product, I am looking at the alternatives.

I use reference managers to keep track of citations and insert them in my papers. I do not store my PDFs or other documents in the program These are my (likely outdated) impressions on the programs:

1. Mendeley: great interface and usability, but unstable and slow to update/fix. Safari plugin makes adding citations very easy.
2. EndNote: bloated and slow, however it seems most commonly used by my colleagues and therefore collaboration may be easier. Less intuitive so simple tasks may take longer, such as jumping between adding papers and referring back to my list of citations
3. Zotero: less attractive UI and not as good at handling multiple citations in a page (inserting a new citation and refreshing the whole paper takes a long time). Also has a great safari plugin

What are your thoughts? What do you use on Mac?