Lens makers these days are coming up with some incredible options that were unheard of just a few short years ago. That continues here, with the Sigma 60-600mm f/4.5-6.3 lens put up against the Sony 200-600mm f/5.6-6.3 in a battle for the title of best wildlife lens. You could also make a case for it being an action sports lens shootout too. So, how do they perform, and which comes out on top?