In short, they’re an enormous company that gets to bypass certain publishing regulations by throwing their weight around. I’m going by what I myself have physically witnessed in the missalette industry so I have no websites I can link to or anything of the sort; but if you know anybody in the biz, ask them and you’ll hear the same answer.
I think Living with Christ is for Canadians, which would mean the readings therein use the New Revised Standard Version translation of the Bible rather than the U.S.'s New American Bible.
That being said. The Word Among Us and Give Us This Day are almost exactly the same as Magnificat in format, the only considerable difference being the “optional” material (such as the tiny editorials or pieces of art between the daily Mass texts). So I would advocate either of them. As for how good they are for kids: well, that I can’t say. Show them and see for yourself I suppose :shrug:
There’s also one called Laudamus Te for the EF (“Tridentine Latin Mass”) that has all of the readings from the 1962 Missale Romanum for the season in both Latin and English, if that interests you.