A few years ago I made the switch to Fuji (X-T1) and sold all my Canon gear. Before the switch I had been shooting kids rec league soccer with a 7D and 70-200 2.8 mkii. I loved the setup, but found it to be a little on the short side once the kids moved up to full field soccer. A 1.4x teleconverter helped to rectify the situation, but I eventually sold everything off and switched to Fuji. I had neck surgery a few years before and required a lighter kit for traveling, so I basically gave up my ability to shoot sports for a lighter travel kit that wouldn't kill my neck.
Fast forward a few years later.. Oldest is now playing JV soccer and I'm wanting to get back into it, on a some-what budget. We're in mid-season right now so I'm giving myself until next year to pull something together. Fuji glass is out of the question as the 50-140 is too short and 100-400 is too slow. Even if the glass hit the mark, the X-T1 just doesn't have the ergonomics for shooting sports. What I'm looking for is bang-for-your-buck used gear targeted at high school soccer. Games will be later in the evening once she progresses to Varsity, so I'm looking for glass I can hang on to for the next 5+ years. I was originally considering another 7D + 300 f/4, but have a feeling it won't be fast enough once she starts playing the later Varsity games. I'm debating stretching my budget out to a used 7DmkII or 1DmkIV + 300 f/2.8 (gen1 / non-is) as well. I'm not locked into a Canon solution either, just not familiar with Nikon's options. This will be hand-held setup, appreciate and feed-back / suggestions / pointers to other options I should be considering.
Final note... There's no professional photography done at the events and it's not a money gig for me. It's just for the team and parents. Thanks!