As webwesen's answer says, all browsers listed on the supported platforms doc should be usable with Confluence.
My personal experience is that using Chrome is a good bet, since most of the Confluence development team uses Chrome day-to-day (or at least they did when I was in the Confluence team). However, Chrome doesn't have a built-in WebDAV client which means that Confluence's Edit-In-Office features do not work. If this is important to you, then I'd suggest Firefox with the Office Connector Add-on installed.