This may be outside the box for you, but a Standard Poodle fits your description perfectly. They are fairly big dogs, exceptionally intelligent, have a real sense of fun, no major guarding instinct (so not reactive, though they have a big bark if anyone comes around the house), are friendly, with a great sense of fun. Also, since there are not overbred like many other breeds, they have not major health or temperament problems. They had an eye issue decades ago, but this has been bred out of the breed now.
I got my first after a Rottweiler situation. I’d always had big dogs. I had a Rottweiler bitch for 12 years and lost her in old age due to cancer. She was fabulous. The house felt so empty after she had gone. After a while, my ex and I decided to get another. Weirdly, we couldn’t find a bitch puppy anywhere, so we bought a dog. I raised and trained him just as I had done with all of my big dogs. Unfortunately, even as a young puppy he was showing signs of aggression. By the time he was 15 months, he was proving difficult to control, was threatening me and if he had got to anyone coming to the house, he would have had them (and he was a very large strong dog). It was heartbreaking, but he needed to be put to sleep. I returned him to his breeder (big successful on the show circuit) and told her that. A couple of months later, the breeder who had put me onto the litter because she had no puppies, let me know that he was the 4th in that litter that had become aggressive in experienced homes - one had bitten a judge in the show ring (so much for its always the owner).
That was all so distressing that I just didn’t want another ‘guarding’ breed. The ex (a Prison Officer) did some research and he said “Standard Poodles” meet all the criteria”. So much for them being girly dogs. We bought 2 pups and I’ve never looked back. This was over 20 years ago. I have had 3 Standards since then and now have 2 Toy Poodles (due to age and arthritis). They are fabulous dogs.