You'll be amazed at how the tiny, cute and funny puppy can be a handful. A little puppy comes with a personality of its own, but like a child it is willing to be moulded in your hands - but this requires months and possibly a couple of years of patience and hours of your time. That includes everything from housebreaking through leash training and verbal commands. You will have to go through stages of teething, chewing, nipping, socializing, adolescence, and much more in the first year of its life. By choosing a puppy, you have the potential to have a much greater effect on his or her personality than if you started with an adult. Your puppy will turn out into the adult dog you make it.
Having an older dog is like having a grown up child. That translates to less trials and tribulations in basic care and training. Older dogs on the other hand are often given up because their owners are shifting to a different city, or discovered they could not give the time required or realized that having a dog was not for them. So, with older dogs, your time would be concentrated in making him or her fit into your household. At times older dogs could come with a baggage from the past if ill-treated previously, under nourished, with separation anxiety, missing the previous owners, etc
There are several advantages in choosing an older dog versus a puppy. One is the predictability of what you will have in the future. You can judge his temperament, size, whether he will shed excessively or not, etc. Additionally, with the help of your veterinarian, you can determine if he has any medical problems such as hip dysplasia, etc. With a puppy, we can sometimes only guess if conditions such as these will develop later in his life, but when examining an adult, most of these problems have already reached a diagnosable stage even if the animal is not yet showing signs.
Having a dog whether from puppy stage or adult is a relationship filled with commitment and compromise. Here it is up to you to make the right decision. The dog is laying his life and hopes in your hands for the next several years.