One comment on Rhodesian ridgebacks. They were bred to attack and hold on to lions. They do not naturally back down from anything. I think that they can be great until they aren't. They are a whole other level of dog ownership and responsibilities from most other breeds.
I have known a couple they can be sweet and good natured. We had a ridgeback/Dalmatian cross (dumbest dog on record, but that was him. Very sweet.). However, I would never, ever, describe them as safe. I would hesitate to see them around kids or strangers, and I would not leave them loose in a yard. An invisible fence is not going to be a barrier. I would not own one personally. A friend of a friend had one turn on his kids one evening out of the blue and he had to fight it off with a large chair. The dog had the owner pinned in a corner and had eaten off the legs by the time the police arrived.
I would Google "Rhodesian ridgeback attack" before you adopt one.
All the best,
Peter