I have a Mark iii and I mostly use single point (center) plus A1 servo. I take mostly photos of wildlife and my biggest challenge is to capture birds on the wing. This combination works extremely well for me. I'm constantly amazed at how quickly the autofocus locks on to a subject.
5DMKIII EOS-M G1X D610 D7100 16-35/2.8LII 24-70/2.8VC 24-105/4 LIS, 70-200/2.8LISII 100/2.8LIS 22/f2 40/2.8 50/1.4 50/1.8D 85/1.8 150-500OS (C) 600EX-RTx2 ST-E3-RT 24/3.5 T-S 18-300VR 50/1.4D 150-500OS (N) YN568EX 055CXPRO4+468MGRC2 190CXPRO4+322RC2 Gorillapod Focus+496RC2 CamRanger B+W filters