Moreover, I want to buy a puppy but I am very confused that which breed I should buy. According to my wife, she is very much in favor to buy jack russell terrier because of his attractive and adorable nature.
JRT's are not a breed for a novice dog owner. They're high energy, easily bored. I've got two Chihuahuas. Not the teacup kind, but the 9ish pound kind. They are funny, smart, good little dogs. They do their business on command, require little grooming beyond an occasional bath, toenail clipping and keeping an eye on their dental hygiene. They are great companions, easy to train and have great dispositions. They don't realize they're small and have a long lifespan (some live up to 20 years), especially if you don't overfeed them. They can be high energy, like our youngest one, who picks up a toy the minute you walk into the house, or very low energy like our 4 year old who doesn't like to be disturbed before 9am. The good thing is, they are small enough to exercise in the house if you aren't inclined to go outside. I'd absolutely recommend a Chihuahua to anyone looking for a smaller dog. I can't wait to find the perfect #3 to add to the gang.