Mind if I ask, just how young and what's your overall touring style? Park commandos? Do you take advantage of resort/pool time?
For us, GF wins big time when it comes to resort/pool time..... both pools have zero entry, lots of seating, the kids splash pad is amazing and hugely important for us. As much as I love CR, the pools there are just a notch below other resorts. Only a dinky squirt area, no true kid's splash pad. No zero entry pools. It just isn't our favorite.
Depending on the time of year, length of trip, and overall plan, I think I'd go GF for the pools alone. If it's a shorter trip, colder months, and not much swimming/resort time in the plan, I'd go CR.
As far as transportation, I love being on the monorail and don't find it to be unreliable at all. The limited hours from a year or two ago are mostly a thing of the past now, so really a non-issue. I've stayed at all the MK resorts quite a bit over the last two years and really can't think of a single instance when a monorail issue materially impacted us.
GF is in a great spot... one segment via monorail to MK.... on boat ride segment back to GF. It's pretty much the next best setup compared to walking from CR.
Good luck deciding.