Chihuahuas are one of the longest living dog breeds. If you are looking for a long term playful partner then Chihuahua is certainly the best choice for you. They are ranked as healthiest among all dog breeds.
This reminds me so much of Nick, a wonderful cat I gave to my son as a birthday present. Alas, Nick was stolen from my son by my grandson Torin. He and Nick have been fast friends since Torin was born.