I left the defaults free for weeks after buying the device, I would simply pick Stock or Chrome 'just once' randomly and see how I got on. After a month of doing this, I've eventually set the Stock as default. It wipes the floor with Chrome imo. There's just something I can't put my finger on with Chrome that I dislike, it's the same on the Nexus 7. I love the way the tabs work on Phone Chrome but other than that, stock browser all the way.