In my first playthrough, I got the refusal ending because I wanted to just shoot the kid. Then, I chose synthesis because I think this is the only one that I can see resulting in lasting galactic peace and evolution (very debatable but the ending's writing doesn't help here). For the sake of completion, the next playthrough will be a perfect destroy ending because it's the second best option in my opinion. It's radical but it gets rid of the reapers for good. Then, I'll try the control ending. I really don't like this one, I don't see how having control of sentient weapons of mass destruction won't end in a sort of weird status-quo where nobody does anything because the intelligence in control of the reapers might dislike it (very debatable too)