Well I'd go 7D instead of rebel then, although I was never as impressed for 7D for soccer as I had hoped (actually felt the 5D2 center point with helpers with more trustworthy overall and the 5D3 is clearly better, I quickly gave up on the 7D the two times
But the AF on the 7D is almost infinitely configurable so maybe you gave up on it too quickly. Its AF most definitely better than the 5D2, in fact it is in a completely different league
I've used my 7d for Soccer, Baseball, Basketball and football and have always loved it! I shoot a 5d3 also and have found that those extra two fps often lead me to the "money shot", where the 5d3 gets fantastic images too, I tend to get the right before and right after the money shots! Like the ball bouncing off the players head for instance...
5D Mark III, 100-400mm L, EF 70-200mm f/2.8 II, EF 24-105mm L, EF 17-40mm L, EF 85mm f/1.8 USM, Canon 580EX II, Canon 430EX II, Promaster TC 1.7x