Certain dog breeds are great if you need a certain trait, but never close your heart to another breed. We foster dogs, and have had all kinds.
My husband loves our Danes; they're simply big couch potatoes but are such elegant dogs when they walk and run. My husband's male Dane goes with him to the office, where the giant dog has his own couch to sleep on during the day after bumming-pets from the office-staff.
My daughter loves high-energy dogs because she is a high-energy person. I always said we'd NEVER had a "pit" or a "pit-mix," but lo-and-behold we ended up finding 3 pit-red heeler puppies, rehomed 2, and kept 1 little female. The one that we kept is the best, most loyal dog we've ever had, and has killed more copperheads and water moccasins than I can count. She is asleep in my daughter's chair right now, ready to go with my daughter into the fields or to check the fences and to kill any "varmint" or snake.
For guarding the livestock, we all love the Great Pyrs. They look like walking polar bears and can kill a coyote, but are so tender and gentle with the tiny goat kids. The tiny kids literally walk all over them! It's amazing to watch them naturally guard the livestock.
Personally, I never liked "small dogs," but now we have a Chiweenie (we bottle-fed her and her siblings for their family after her dam died unexpectedly. She was the runt of the litter, for a long time being less than a pound because she had a hard time keeping milk down), and she is a complete spoiled mess. It's impossible NOT to love the scrappy little 5 lb. thing that somehow has survived in our family. (We had to put bells on her collar to keep her from being stepped-on, and to find her when she "disappeared" behind or under furniture.)
My FAVORITE dog, however, is my border collie (he may be mixed with blue heeler). We rescued him as a tiny puppy, almost bald with mange, and close to death. My husband did not think he'd survive the night. Now, about 4 years later, he's asleep in my chair on a plush blanket. He's also spoiled rotten, but in a good way, and expects to not only go everywhere with me in the truck, but even "ride shotgun" in the passenger seat. (He'd probably try to drive if I'd let him.)
Dogs are such wonderful animals. I'm so glad that medicine and science now are recognizing the health benefits of having pets, especially for the elderly and the depressed.