Out of your list nothing looks kid-proof (except maybe the trigger Z, but I don't like that board)
Something like a Filco, KUL (only TKL), or a Ducky Shine 4 doesn't have many bits that a kid could break off.
Out of the 3 I listed, my favorite is the KUL, but it only comes in tenkeyless. It's pretty much invincible, though. My foot was in worse shape than the keyboard after I dropped it.
The Filco Majestouch 2 full size is a tried-and-true board, though hard to find in the US.
The Ducky Shine 4 has some nice backlighting options, which could be good for the kids. Pretty lights are always a bonus for kids. I don't know much about the quality of the DS4, but if it's anything like past ducky boards (I have a DS3 and a friend has a DS2) it should be pretty good. I've heard nothing bad about the DS4 yet.'
That's just my $0.02. I'm happy to answer any more questions you've got.
And also give me that cherry board when you're done with it >: )