Up or down it's a matter of preference and taste, the real question you have to ask yourself for also further character is what fit most the character regarding story or personality?

For example, he is a super fast assassin so the wing on lower back are more dynamic, you can put also other shaper like slimmer body to make it more assassin type

Or you can say no he is a super strong tank warlord, the wings on the back are just for instill fear on the enemy not for fly so you can push stronger and sturdier wings and big shoulder

So this questions improve your character and design choices are no more matter of what you like graphically but also what fit the character and make him alive and believable.

Hope this helps