I have the opportunity to purchase exactly one of the following lenses (Canon): 24-105mm f/4 L IS 24-70mm f/2.8 L 70-200mm f/2.8 L IS I've ready any number of threads comparing the 24-105mm and the 24-70 and I still can't make up my mind. I throw the 70-200mm in there because this might be my last chance for a while and hey, who doesn't want one? I only have a 50mm f/1.4 in my bag at the moment which is great for general every day stuff and whatever semblance of portraits I do. Lately I've gotten into more event shooting such as company events, parties, etc. I frequently shoot moving subjects in questionable and sometimes low light. So that plus moving into more formal portraiture are my two main areas along with still life. With the 50mm, I'm finding myself either cropping images heavily or unable to get the shot because I can't back up far enough due to close quarters, etc. Obviously a 70-200mm isn't going to help at all with the latter problem, but I'm going to keep it under consideration. So I guess I'm soliciting opinions on what lens might be the best for me and why. Thanks for taking the time.