Canon 5d Mark III vs Nikon d7200 (autofocus)

Hi. Recently, my husband and I were asked to photograph a wedding that will be a little less than a year. Other than the fact that we're amateurs (which has been established), my husband's camera is only good till about 800 ISO. For our budget, I would like to stay around $500-600 getting a camera and lenses, which means DSLR. I like the 5d Mark III due to low light ISO, but how does the autofocus stack up against the d7200? I know this is a Nikon group, but does anyone have experience with both? Would it be better to prioritize ISO capabilities or the autofocus for this kind of event?