Puppies are not for everyone. Buying a hypoallergenic dog that is a year or older is the answer for those who have limited time to train their dog. Young adult dogs are still active, but they are less curious than puppies.
If you want a dog that enjoys getting exercise, lets you know when they need to pee, and sleeps for longer periods of time, then a young adult is the right dog for you.
Depending on the breed, you will have to board your dog when travelling as some breeds can panic when left alone.
Dogs that are five or older can usually be found in animal shelters or dog pounds. These dogs probably had previous owners and were either abandoned or mistreated. If you want an older dog that will require even less training than a young adult, then you should visit your local animal shelter.