The 70-200mm f/2.8L IS II is a great lens, and delivers very good IQ when used with a 1.4x extender; however, at 280/300mm, the 70-300 L will have a slight edge. The 70-200 II is also, large, heavy, and expensive. It is more versatile in that it's great for portraits, etc., but it's a lot of lens to carry around. Still...I love mine!