Congratulations on your new baby!

I have some questions for you:

How much time will you be able to devote to training your new puppy?
Is your dog going to be a guard dog, or a companion?

1. A Rhodesian Ridgeback is a good breed. As long as you socialize him well, he should be fine. They do well with a companion dog, so it's a bonus you already have one.
2. Belgian malinois are excellent dogs, but they require a LOT of energy and attention. A LOT. They bore easily and turn into destructo-dog when left to entertain themselves.
3. GSD are fantastic for families, especially with children. We had two when I was growing up, and the dogs were our nannies, keeping an eye on us kids. If you go with this breed, be sure to get them checked for hip dysplacia.
4. Cane Corso? Really? Why would you consider this breed? Every Cane Corse I've known had issues as far as temperment- not to mention the fact that they're great clumsy galoots that tend to be as delicate as a bull in a china shop.
...and perhaps the saddest point of all: the larger the dog, the shorter the lifespan. A Cane would likely not live long enough to see your eldest graduate.