Ooo new dog, fun! For a first time dog owner, I'd recommend looking at the adult dogs at your local rescue or pound. Puppies are A LOT of work-they will eat your house and use it all as their bathroom! With a rescue you can get an adult dog that is already trained, and you already know what you're going to get, whereas puppies all kind of have the same personality! Your breeds are are rather diverse (terrier, retriever and corgi all have different sizes and personalities, so you seem like you're not quite sure what you're looking for.
Many people believe a rescue dog will be a lot of work because they are somehow abused or unwanted, but most of the time they end up at the shelter due to the owner's economic or housing troubles.
As for picking out a dog, you can look online profiles of dogs at rescues or shelters. If you select a dog from a foster-based rescue, it is already living in a temporary home and you'll know the most information about its personality, and you can find dogs to adopt locally online- try websites like petfinder.com or petango.com. If you walk into a physical shelter, the best way to find the perfect dog for you is to tell the volunteer or shelter worker that you're a first time dog owner, (you can also think about how big you want your dog to be or how much time you'll have to exercise it) and ask what dog they'd recommend. You could also walk around the kennels and pick out a dog you have the best 'connection' with, but sometimes kennel behavior is misleading- a cage isn't a natural environment and sometimes the barkiest dogs inside are the calmest outside and vice-versa, so the best option is asking for a recommendation from someone who knows the dogs. Another added bonus to rescue dogs is that the adoption fee is much cheaper than purchasing a puppy from a good breeder- at most county pounds its around $25-90, and maybe $200 or so for private/no kill shelters, and that includes vaccine, license, microchip, and spay-neuter.
At a shelter, you will get to take the dogs outside into a play yard or greeting room, where you can pet and play with the dogs, which even if you're not adopting that dog, will help you figure out what sort of personality is best for you.
When I adopted my pit mix Bonnie, my family and asked a few volunteers what dog they'd recommend that would be medium energy, medium size and good with other dogs and kids- and they all said Bonnie! I was skeptical seeing her in her kennel; she had been there for five months and was so shut down she didn't want to come up to the front of the kennel. But I trusted the volunteers and when they brought her out on a leash, she was the sweetest dog ever! Out of the 200+ dogs at that pound, I'm convinced I picked the very best one! Knowing my GSD mix is picky about other dogs, and the shelter didn't allow dogs to meet before going home, I picked her partly because she was the dog they used to test if other dogs are friendly towards others. It also goes to show that there's sometimes surprises of what's expected for different breeds- pits are known for not getting along with other dogs very well, but she is rock-solid when interacting with any dog. She also came home already knowing how to sit, shake, stay, and being potty trained!
On top of the bonus of finding the perfect dog-owner match, there's the obvious benefit of knowing you saved a life (even if they're from a no-kill or low-kill shelter, adopting helps free up kennel space and help rescues run, and therefore tackling pet overpopulation). Breeding dogs is great for their breeds, but to the average dog owner, a rescue is just as good, if not better. Mutts are often a great choice and tend to have less chance of genetic diseases (For example, Goldens are predisposed to cancer so much that about 60% will die from it, while labs often have a mutation of an appetite regulation gene that makes them obese) but if you want a purebred of whatever breed you love, if you keep looking online, you can certainly find it in a rescue, probably even for less wait time than if you were waiting on a litter from a breeder.
Hope this helps!
