Yup, old topic but worth noting for the research others are doing...
Assuming that "interviewing children" means "talking [little]head" then a vote for the 100mm on a tripod for -- *most important* -- not being right on top of the child: too scary! Then you have the softer background, other good image stuff. I would hope an interview would use a clip-on mike.
Even true for crop sensor IMO. (I had a ten year stint as an elementary school teacher. Kids need space until they are a little used to a new adult. Many grown-ups, too!)