The 135L is great if thats all the reach you need I love mine, and the f2 will help freeze action, the 70-200 f2.8 is a very, very versatile lens but IS will not help freeze action. But for video the 70-200 is the better lens. Since you have to control your shutter speed, the IS will help a lot, specially hand held. I also have the 50L and while it lives on my camera, my next lens will probably be the 85L, if I start doing more event work I will probably get the 70-200 f2.8 instead. As an example I took some pictures at a dimly lit venue with my 135L I got some good images but in that case since there was not a lot of fast movement at the same iso I could have got a closer framing and a slower shutter speed with no loss of sharpness. With the 135L you really need to keep your speeds above 1/125 .