Zotero has been great. I switched four years ago and never looked back. Plugin support is great- I have drag and drop support in my latex editor and fairly easy citation selection in Lyx
I love zotero, and would never switch to Mendeley because of the lock-in problem, but the lack of any mobile apps is a real problem. Reading and annotating on an iPad is a key ability, and the 3rd part PaperShip is buggy and no longer under development.