I’m amazed that only one other poster recommended my favorite:
SHETLAND SHEEPDOG aka “Shelties”
They are sweet, not too small, not too big, very patient. They will herd your kids away from strangers (and water; they don’t usually like water). Ours loves to chase feet; not people, per se, just your feet. They run in circles when excited. They are total homebodies. Ours got out of the fence one day (we think the meter guy left the gate open), and Duchess just sat on the front porch, one bark every 30 seconds, until we realized where she was and opened the door. Badly bred dogs have given the breed a reputation for yapping, but ours never does.
My DD bugged her too much once (DD was about 14 months and had the dog sort of cornered; usually Duchess would just walk away when she’d had enough). Duchess snapped her teeth in DD’s general direction to tell her to stop it. Duchess had never done this before (and hasn’t done it since, either), so DD was startled and started tearing up, but before she could actually start crying, Duchess was vigorously licking her face to apologize and DD wound up giggling and trying to run away from a slobber bath!
When DD and DS came home, Duchess sniffed them coming in the door, then quickly figured out that they were now part of the herd. Being the smallest, they obviously needed guarding, so she positioned herself alertly near wherever they were napping. (She also gives us adults “the look” or a single bark when we’ve stayed up past our bedtime.

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We adopted Duchess from a Collie/Sheltie rescue association. Her previous owner had had a stroke and couldn’t take her into the assisted living facility, so the owner’s son rounded up what vet records he could find and gave her to the rescue association.
We only brush her once every few weeks, and the vet says she’s the best groomed Sheltie in the practice, so don’t let the fur scare you. (although there is the fall and spring “blowing coat” when there are little tufts of fur around the house for a few weeks… you just have to brush a little more.)