What type of dog would be good for me?

I have a two level house ( and a basement) and a large backyard. I'm not looking for a small, purse dog. It could be medium sized to about a German Sheppard? I have a Shetland Sheepdog & a Dachshund, btw.Not too much shedding, and friendly with a family. I'm all for a shelter dog too, but pitch me some ideas of breeds? Thanks.