I would go for a collie, we had one growing up as kids and they are the greatest, loveable, loyal large dog I know. My parents have a German Shep. right now and she was a sweet heart with my hounds she wouldn't harm a flea, but in her older age she is getting a little snappy and I can't trust her alone with them, I also can't trust her with my cat (or rabbits, we had a terrible mishap with her and my rabbits). If your living in an apt. I do think that little dogs would be better, but do your research some little dogs would not be happy in an apt. either. And I wouldn't get a sheltie instead of the collie just because it looks like a smaller version, you would be disapointed they are not anywhere near as nice of a dog as a collie is. (personal oppinion, I don't want anyone mad at me :0) My mother has had 6 of them and they are not my favorite breed)
But it is totally up to you, if you like the big breeds, with daily walks Im sure they would be just fine :0)