From what I heard the 70-300mm is soft at 300mm. It is a slow lens and based on your needs, I would discount it. The 70-200mm VR is an excellent pro quality lens. The vignetting only shows up with FX cameras. Most of the time it is not concerning to me as I crop most of my sports photos. I also hear the f4 is a very nice lens compromised only in 1 stop, but the less weight and cost make up for it.