How do i decide which dog?

i have a 6moth old alsation (rambo) he is very good and very exciteable. im moving into my mother-in-laws house (where rambos mum dad, and big brother live) she is moving away with her dogs which leaves my dog on a farm with 5acres. i want another dog to go with him as dont want him on his own all the time but i have a problem. me and my partner cant decide which dog we like a Doberman or Rottweiler but i have to think about Rambo first as dont want him feeling pushed out when i bring in another dog. He is very good with his parents and brother and also very good with dogs met on walks etc. can someone help me please thanks xx