Why would you ever use auto white balance ?
Pretty much every camera I've used that has AWB universally gets the temperature wrong at some point, and I know I that my own guess at the Kelvin temp is always better.
I would only use auto white balance if I knew that the color balance would be constantly changing, otherwise I either use my color meter and set the Kelvin measured by the meter, or take my best guess at what I think the actual Kelvin temperature is and go with this. ( I can usually guess within a couple of hundred Kelvin of what the true Kelvin temp is )
Custom white balance would be ideal, but when shooting event work outside, that is a recipe for disaster. All it takes is for one cloud to roll overhead or the sun to peek from behind an otherwise overcast sky, and your footage is toast. At least you have a chance with AWB to not completely lose the footage.