I agree with Ernie that this seems to be a ridiculously common thread topic with no real answer because it depends upon the photographer and situation.
There is no perfect/favorite overall lens and no matter which lens is on your camera at any given time much of the time a different one could be better. I.E. for HS football at night, my usual setup is a 300 F2.8 on the 1DX 2 and a 70-200 F2.8 on the 1DX HOWEVER there are times when the 400 2.8 would have been nice and other times the 200 F2 would shine. And there are also times I wish I had the 24-70 F2.8 on the second body instead of the 70-200 but I am playing the odds and the 300 / 70-200 setup covers most of what happens during a game and the 300 is MUCH lighter than the 400 and with its slightly wider field of view it is easier to make the jump from QB release to the ball arriving at the receiver. One thing that sets these primes off from other options is the focusing speed is extremely fast in low light which is where many other lens including most zooms begin to have a weakness.
For daytime soccer, I have used my lightweight 400 F5.6 often because it is an easy lens to handle and run with for long periods of time and although not as sharp as the big 400, this is one case where weight makes a difference. Although not the absolute best glass Canon makes, the 400 F5.6 and the 135 F2 provide excellent IQ at a very reasonable price. I think the Canon 200-400 F4 with integrated 1.4X extender would be a great lens for daytime soccer with its wide focal length range but I haven't tried it yet.
To make the lens that you currently own your favorite lens, learn how to get the most out of it which means start with your placement and then figure out the best combination of the exposure triangle so that the lens can show its best behavior. The best glass is nearly as good wide open as it is closed down one stop but a lot of glass is much better a stop or two removed from wide open so reducing shutter speed or increasing ISO to allow stepping down the aperture can make a big difference in performance. Every choice involves trade-offs but wise choices minimize the impact of those trade-offs..
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
