- Passwords - Bookmarks - History - Open tabs on other devices - Extensions - The list goes on
You can say the other things about Chrome and Chromium (as of recently, even the encryption part) but I do not see the docs, the code, and infrastructure published and public like Mozilla has done. Hell, someone even built in a sync mechanism in PHP to ownCloud, to make it more useful.
It is efforts like this that make me, despite other warts, a militant Firefox user. The software is ok, but an institution that pushes standards and worries about my privacy, the whole shebang, is really worth it to me.
I tend to use it more as a history of sites that I've looked at though, for research I would use Zotero.
Those are the questions a service has to answer for it to leave its mark, IMO.
Also we gonna build a tool that everything you collect to dragdis would automatically go to dropbox, gdrive or skydrive.