I have a woz and hobbit. Kids love both and have depth on both for advanced players. I took kids to play a GB premium and they all left saying it was cool, but didn't want one due to difficulty. They fully understand hobbits rules and can advance. Between your options listed, I would think MMR is better for family, but I would prefer GB as a more difficult challenge. MMR can get old fast. If you're open to other ideas, I second the hobbit or DI.

I totally agree with you. They all get stale, but some are easier to get burned out on than others. I love mm, but after playing it in the wild a while, I knew right away I wouldn't own it. Everyone has different takes, and opinions and that's OK. The best advice anyone can ever give in this case is simply to go play each game your interested in before deciding.