I know this topic gets debated a lot but I'm still not sure what I should do so I'm going to throw my situation out there and see what you guys think.
I currently have a 70-200 f/4L IS which is my go-to lens, and also have a 50 f/1.4, 85 f/1.8, and 135 f/2L. I just picked up the 85 and 135 recently (used), as I wanted something faster than the 70-200 and wasn't sure which focal length I would use more. I've only played with the 135 a little but my main subjects have been (and will continue to be) my young boys and my dogs. What I found, as one would expect, is that it's an amazing lens when it's the right focal length, but when your subjects are active and moving, a zoom will get you a lot more shots.
I debated between the f/4L IS and f/2.8L IS II when I first got my 70-200 and have been second guessing myself ever since. The main issue was the weight, and that's why I thought the 135 f/2L would be a nice complement, but I just don't know how much use it's going to get. The thing is, if I end up carrying the 70-200 f/4L IS, 85, and 135 all along, I'm carrying as much if not more weight than the 2.8 anyways, though granted not all mounted to my camera at once.
My other dilemma is that my son just started youth soccer, and I'm finding that the 70-200 isn't really long enough there. I've already debated a 300 f/4L, but I don't really want to stick more money into lenses, which means I'd probably have to sell the 85 and 135 to fund it. It seems that I might be better served by either of the 70-200's and either the 1.4X or 2X TC, of course the 2X would only be an option with the 2.8.
Bottom line, my boys will always be my main subjects, but that includes formal portraits (indoors and out), candids, sports, and school events. Please help me make up my mind once and for all... stick with what I have or make the leap?