Everybody will have an example of the "perfect" dog breed, as the great comments above demonstrate. It's a lot like choosing a greeting card for someone else to give: It doesn't always hit the mark, and everyone has their personal preferences.
Acquiring a pet, (whether through adoption or purchasing from a reseller), is a lot like buying a timeshare. It's very easy to get into one, but can be difficult to get out of one. (See what I did there? LOL!) Just like with timeshares, do your research to make sure the pet you take on is a good fit for you and your family.
Dogs, and dog breeds, are as varied as anything you can think of. Over the centuries, hundreds of dog breeds were developed for specific tasks. Form followed function. Greyhounds were bred to run. Huskies were bred to pull dogsleds. Lhasa Apso's were bred to be palace watchdogs, to sound the alarm, if an intruder happened to get past the Mastiffs guarding the perimeter. A lot of breeds were derived from other breeds, until today you can pick size, color, lifespan, general temperament, even non-allergenic traits. It's a buyers smorgasbord of options. So-called "Designer Dogs" are the worst of the lot, as people indiscriminately pick two dogs they think would make a visually interesting mutt, and breed them on and on. It's all about the money, with little to no consideration about health issues, poor genetic traits, and the general fitness of the resulting animal. These people are doing a terrible disservice to the dog world.
It's important to do your research, because even though exceptions exist to every dog rule, it isn't a fixed situation. I've known dogs that were calm and loving to their owners, but were completely out of control with anyone else. Who will watch your dog when you're away? You can't always dismiss bad behavior with, "Oh, sorry, he's excited." A wet-nosed puppy that is playful and fun and loving, will turn into an adult within six months to a year. Five pounds can easily become fifty pounds. Keep in mind the adult version of what interests you, because that cute puppy will never be this way again. Just like with children, they grow up, whether we like it or not.
I work with an older woman who was lonely, and adopted a Lab mix puppy. They loved each other, and she was devoted to her puppy. Nine months later, the dog was destroying her house, because the woman was unable to properly train or exercise it. It wasn't housebroken, barked incessantly, and dragged the poor woman down the street when she tried to walk it on a leash. She would cry at work about "What am I going to do?" She had no idea what she was going to get into.
I'm a socially active person at my work (I work for a hospital, and have a lot of people around me.) Through different conversations with different groups of people, I knew another woman who's daughter and son-in-law had just lost a younger Lab they'd adopted due to congenital heart issues. They'd mourned the loss of their dog, and wanted to adopt a young adult companion for their aging Golden Retriever. They wanted a dog that would be a good fit, and who would enjoy living on a five acre property on a lake with a long beachfront. Long story short, I put the two women in touch with each other, several meetings occurred, play dates happened, and the daughter adopted the older woman's Lab. They are all great friends, and the change is working perfectly, especially for the young female Lab, who now has manners, limits, and proper behavior. Best of all is she's exhausted at the end of every day from playing so hard, and she sleeps soundly every night. The former owner has full visiting rights, which everyone considers a win-win. Happy ending.
I offer this to give you even more to think about, because I know you don't have enough to think about on this already. LOL!
I hope you find the perfect dog - for you. Good luck!
Dave