Border collies are lovely dogs, but they can be a lot for a new owner who isn't prepared for a challenge. They're definitely very smart, but they need regular (often daily) mental stimulation to be happy. They're a sensitive breed, and not very forgiving of handler mistakes, ie if you reward the wrong behavior a single time, you're likely to spend ages trying to re-teach things the 'right' way. It'll depend some on the individual, but I just don't want anyone falling into the trap of thinking a smart dog is always an easy dog, you know?
J10055, you say fur length doesn't matter, but how much grooming are you willing to commit to? I'm fond of poodles, but they will need regular grooming even if you keep their fur cut short. They come in several sizes too, of course. They can be energetic as well, and do need mental stimulation, but aren't as demanding as border collies tend to be. You might be able to find a breeder who's producing service dogs or therapy dogs (these are the ones that visit hospitals and elderly homes), which is often a good sign that their adults have a very confident, laid-back temperament. Other breeders might produce a lot of competitive sports dogs, for example, which are great for some owners but probably not what you're looking for in terms of drive and energy.
Of course labs and goldens are popular breeds for a reason, too, and many would fit with your requirements perfectly. Just keep in mind that they can be little hellions as puppies!
Granted, most puppies and adolescent dogs can be A Lot, and need more attention, interaction, and overall effort from their people than an adult. Don't overlook a 2+ year old shelter dog - there's a lot of them out there that'd fit your requirements. A friend of mine just got an american bulldog mix who's the sweetest thing under the sun, great off-switch inside, and already had good house and leash manners.