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.
Canon 5DMKIII EOS-M G1X | Nikon D610 | Sony a7 | 16-35/2.8LII | 24-70/2.8VC | 70-200/2.8LISII | 100/2.8LIS | 22/f2 40/2.8 | 50/1.4 | 85/1.8 | 150-500OS | 600EX-RTx2 | ST-E3-RT |24/3.5 T-S | 28-300VR | 28-70OSS | HVL-F43M | Manfrotto 055CXPRO4+468MGRC2 | 190CXPRO4+322RC2 | Gorillapod Focus+496R