Safari for every day browsing. Never had a problem with any sites not working or anything.
I use Firefox just for linky extension on a site i moderate. Just makes it easier to open 20+ links from a page, in tabs at once.
but, I use IE when in Windows and still revert back to Firefox for linky.
I used to be a hardcore firefox junky, way back when it was first forked from Mozilla's nutcrape suite as Phoenix (before the name change to firebird, then firefox). The main aim was ultra light weight, fast browser. It did well and out performed Microsoft's IE on load times and memory usage. It was amazing. However, that time has long gone and I tried IE when Windows 7 came about and I haven't looked back since.
Firefox was a great browser, but it's just as bloated as the rest it was trying to get away from at the start.