I think a lab or golden retriever would suit you best
I have a Jack Russel service dog (hearing dog, jack russels have AMAZING hearing!) and love him to death. I lived in an apt when I got him, so had to choose a small dog that could be trained as a service dog. When I get a house of my own after I graduate, I want to get a lab and get him/her trained as a second service dog. By that point, my dog will be 9-10yrs old, and I think already having the new dog before the first passes would be better for me emotionally. As well as needing the dog to wake me up every morning, lol.