I'm coming off of FINALLY playing both endings to Phantom Liberty. So going forward, I am aware of the context of everything.
I hate saying this, because the character of Songbird is a very well written character, but I dislike the "Betray Reed" ending.
The reason that I say this is because of mechanical and story factors.
On the mechanical side, the Betray Songbird ending is more fun. The fight with Hansen, Max-Tac, and the stealth aspects are more fun to me. I really love that it turns into a horror story towards the end at Cynosure. As I played it, I couldn't help but think of System Shock 2. Seeing Songbird turn into a SHODAN-esque character was really cool to see. Seeing the Blackwall corrupt her and being completely powerless towards the end hiding from the Droid was really fun. Everything felt earned and was really well paced.
Story wise, I loved seeing context for Song's past and her recruitment. I also loved seeing the emotional distress of Reed as he tries to hold it together, but you see that he is conflicted on what to actually do. When it comes down to the wire, I mercy kill Songbird. She is too dangerous to be left alive, especially in the context of the Blackwall's corruption and the fact that Myers is using her as a weapon.
Playing the Betray Reed ending felt hollow. Reed quickly became a stereotype in that ending. I hated that, because Idris Elba does a phenomenal job in everything leading up to that ending. Add to that, Song's escape feels hollow too. Sure, I have sympathy to her because she's dying, but I genuinely don't think there was enough to make her completely justified in her actions.
In conclusion, I did enjoy playing a different version, but if I had to pick, I have to side with the Reed route and mercy kill Songbird. It just feels right to me, and I enjoy it better than the Song route.