At this point in my life, I have to have AF if I want a descent picture of one of the kids (or grand kids) running around the house or yard. Just cannot do it with a MF camera anymore.
The automation (or the part of the automation I use) is what allows me to get the picture I would not have been able to get in the first place with MF. Believe me, I have tried.
For me, I have found that kid (people too) photography is where my heart is. Not really motivated to get the landscape shot or something like that. Can't really do it well, perhaps that's why. Working on it though.
Getting that intimate, candid, and natural photo of a kid engaged in life is what gets my photo blood going. I have got to get out and shoot more!!