Personally I swear that standard poodles are the best dogs in the world, but they are not on your list, lol.
I have a boxer, she's a great dog, very outgoing and loves everyone she meets. But when I adopted her from the pound I was told that she was turned in because she played too rough with the kids, didn't bite, but did scratch with her front legs, a trait boxers are known for and she does do it when excited. My 15 yr old God daughter, who is a tiny thing, comes over and plays with her all the time, she's great with kids. She is energetic, but you are a young so should be no problem with you keeping a boxer exercised.
My adopted son is the biggest, blackest German Shepherd I ever saw and he is a wonderful dog, I'd take him in a heartbeat. I often walk my dogs through the back fields to get him and we all go on a long hike. The only thing about him that I would warn you about is that he is very gentle and loyal to those he considers family, including regular visitors to his home, I can do anything to that dog, but he's very defensive against strangers. He is controlable in that anyone he considers family can tell him to back down and he will, but I think that a shep needs someone willing to put a lot of effort into training because of this trait. I had one for a short time as a teenager, my parents got rid of her because I did all her training so she was totally loyal to me. She didn't have a mean bone in her body, but she would only respond to me.
I won't go into Rotts because I'm predjudge against them thanks to having irresponsible neighbors that own them, the only breed of dog I feel this way about. I won't go into all the trouble those dogs caused me, just say, it was the only time I feared for my life on my own property and they ended killing my mini poodle and pug cross. I understand they are great dogs in the right hands, I just had the misfortune of have two around me that were in the wrong hands.