Either a Sheltie - Border Collie mix, or just a Border.
Smart beyond belief, friendly to all who deserve it, protective - but non-aggressive until required.
I replaced my last BC with another - which was stolen within 2 months. "The Warden" hasn't been ready for another since.
Two heartbreaks in 2 months were a bit much.

Mark

I've always been a curmudgeon - now I'm an old curmudgeon.
~Molɔ̀ːn Labé Skýla~