Border Collie
The Border Collie is an extremely active dog. Bred to work hard in harsh conditions for long hours at a time, this sheepdog needs a lot of free running in order to maintain his mental health. A daily walk on a lead will not do.
The Border Collie's popularity has spread from his position as the world's no.1 herding dog, to the world's no.1 Competition Obedience dog. As such it's virtually the only dog breed still selected on the basis of its brainpower. Hence there's quite a variation in appearance between dogs.
I've had four Border Collies - two from Obedience Competition breeding, one from International Sheepdog Trials, and one from rough mountain work. But they all share the same high activity levels, alertness, curiosity, and eagerness to learn. They have all also displayed high levels of devotion and loyalty.
One was "on a short fuse" and needed careful handling around other male dogs. The two from a herding background would either like to speed visitors off the property, or prevent them from leaving! All of them are remarkably useful around the house, fetching things, picking things up, shutting doors etc.
They are all easy to leave with other people when necessary, travel extremely well (although one was carsick as a puppy), adapt well to strange surroundings, and are very biddable in the home. But the Border Collie does need skilled handling, and some level of formal obedience training is indispensable.
The two brought up with children are excellent with them, the two brought up without them were unreliable, which emphasises the need for early socialisation and "proofing" against all kinds of experiences and events.
With his exceptionally acute hearing (think of those vast sheepy hillsides where the breed originates) the Border Collie suffers from fireworks and many are unsteady to gunshot without a lot of specific noise training.
Some Border Collies are always on the go, and don't seem to have an off-switch. If you don't wish to be herded everywhere you go in the house, or have toys and socks presented to you endlessly for games, or live with a dog always on high alert, then skip the Border Collie.
I couldn't recommend a Border Collie to a home where he does not have work - either herding or some kind of competition-level obedience. Though I'm sure there are some well-adjusted collies in pet homes, I don't think mine would have lasted long in one! BJC