I would recommend the Coast Guard for anyone who wants to not be involved with the killings of many people and mostly doing good. Sure, there are a handful of roles that do kill, but the vast majority are involved with things like search and rescue or ensuring shipping is done safely, and things like that. They also deal with drug smuggling, which has some ethics issues as well, but as far as military service goes (and getting the benefits from it) it’s easily the best choice.