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 5DMK3 70D | Nikon D610 | Sony a7 a6000 | RX100M3 | 16-35/2.8LII | 70-200/2.8LISII | 100/2.8LIS | 100-400LIS | 40/2.8 | 50/1.4 | 85/1.8 | 600EX-RTx2 | ST-E3-RT | 24/3.5 T-S | 10-18/4 OSS 16-50 | 24-70/4OSS | 55/1.8 | 55-210 OSS | 70-200/4 OSS | 28-300VR | HVL-F43M | GoPro Black 3+ & DJI Phantom