I have had a few rabbits neutered over the years, and I have known many rabbits at the Sanctuary where I volunteer that were neutered, and none of them had personality changes. It is strange that those 3 females became aggressive after spay surgery. That is not common, and I wonder if there isn’t some other reason why they became aggressive. Rabbits can go into a post neuter or spay craze, due to fluctuating hormone levels, where they might exhibit some bad behavior or act a little changed, but that only will last a few weeks, and it only happens in some cases. I have never had it to happen.
Most rabbits do love to have another rabbit companion, to cuddle with, to groom, just to be with. But it occasionally happens that a rabbit prefers to be the sole rabbit in the house and bonding isn’t possible. It is rare, but everyone should be prepared when they get a second rabbit, in case they never bond and the rabbits have to be kept separately. If you adopt from a rescue, the new rabbit should already be spayed or neutered, which saves you money and means you can start the bonding process sooner. The new rabbit would need to settle into the house for a week or so even if it is spayed or neutered, before bonding is attempted. A month should elapse after your rabbit is neutered before any bonding sessions start. It is usually easier to bond a neutered male with a spayed female, but you can bond same gender rabbits too.