How old are the kids?
My grandkids have The North Face Tigger bags, which I bought when they turned 5. They are nice and warm and launder easily (important with children who still have occasional accidents at night). I strongly recommend them for kids under 10. The newer model (they have the old) is lighter, which is a bonus. The kids have used these at home for sleepovers, too, so they have gotten a lot more wear than just camping. Both bags are still in excellent shape and, surprisingly for a synthetic bag, seem to have all their original loft.
A year ago, I bought a close-out on the REI Sub-Kilo bags for my oldest grandson, who is now 10 and several years past the night-time accident problem. His 5-year-old brother is now using his Tigger. I would not buy a down bag for any child who has not gone at least a year, preferably longer, without accidents at night. I also bought one for his 8-year-old sister, but it is being held until she is older–she still has an accident every month or two. These bags, while too big now (I tied a cord around the excess), should last until they reach adulthood.