Border collie/Lab mix VS Shetland Sheepdog (Sheltie) I have some questions! PLEASE answer!?

I don't know too much about Border Collies or Shelties but right now I do have a lab mix and from what I have experienced and heard, labs aren't all that great with younger kids, there are some that do really well with them and in the case of our dog, we have to crate him whenever kids come over and be really careful around strangers. As far as shedding goes I am always so surprised to see how much is shed in a weeks time year round. I don't think having one person home at all times would really annoy any dog, just so long as there isn't always someone pestering the dog (they need their alone time too) They should be just fine. Our lab mix isn't much of a barker, he only really barks when someone comes to the door or is walking by our yard while he is out there. I have never met any dog that loves to run as much as the one we have now, he requires a lot of exercise and gets most of it from me taking him on runs, throwing the ball (Definitely invest in a chuck-it if they like to fetch), and swimming. I know this probably doesn't help much but figured I would let you know my lab-mix experience! Good luck on getting a new dog!