Getting a 2nd puppy, but what breed should I get?

I have an 11 week German shepherd puppy who I finally potty trained! Who Hoo! I’ve heard puppies could be overwhelming, but I don’t think it is so bad! I love having him in my house and he is a playful guy. Very smart and learns fast. I decided that I want a 2nd puppy as well for various reasons. The main is I love the company! The fact that they can keep each other company during the day when I am at work is a big bonus (I come home for lunch and walk him so don’t yell at me… lol). I’m uming I should get a female dog so they get along better. Is this true? I’m not looking at breeding so I don’t want to get another German Shepherd, I was thinking maybe a Pitbull. What is a good breed based on behavior that would go well with my GS pup?