I was born into a house with both and grew up with both - a Sheltie and a Bouvier des Flandres. My mum was really into training and had done a lot of work training and showing both our and other people's dogs, so needless to say our guys were really well mannered. We haven't had dogs since they passed, but now that we're looking into a dog again I'm really pushing for a big dog.
For me, if it doesn't at least come to my knee at the shoulders, I don't really see it as a dog. My favourites are Dobes, Coonhounds, Foxhounds, Wolfhounds and Deerhounds.