The best kind of dog for you is not the one that looks good, but the one that best fits your lifestyle, personality and living conditions. A decision should not be made based on breed or a knee-jerk decision about the dog's initial age.
Research is the most important part of finding the right dog. While individual animals vary in temperament, a look at the characteristics of its breed or its dominant breed is a good place to start. Look for a breed that has an energy level similar to yours, has grooming requirements you can accommodate, and is the right size for your home. For instance, an Australian cattle dog is almost certainly the wrong choice if you live a sedentary, apartment-dwelling lifestyle.
The other important decision when choosing a dog is its age at the time you buy or adopt. Puppies take a lot of time and intensive training, while older dogs are more likely to settle into your routine quickly. If you are away for more than three hours at a stretch and do not have a caretaker, then you likely cannot manage a puppy.