Most dogs can be friendly, given the right circumstances AND the right owner.
Unlike Pitbulls, which were bred for small animal prey drive, Rhodesian Ridgebacks were bred for aggression towards large predators e.g. lions.
Are you an experienced dog owner? What's your experience with large and powerful working breeds? What's your wife's experience?
The safest bet would be to get two puppies, OR an older small dog and a ridgeback puppy.
But again, Rhodesian Ridgebacks are very large and powerful, and need owners who are capable of raising and controlling them.