I would have preferred superman not to kill, it only becomes an issue for me if they ignore the consequences of it and don't address it in BvS or if they just have him keep killing. Superman shouldn't be ok with killing (he obviously wasn't at the end of MoS), but when the situation absolutely calls for it he should be able to make that choice. Leave the unrealistic ultimate Kantianism to Batman. I'm curious to see what WW will be like, she's usually less adverse to killing (but still doesn't revel in it).
I always saw it as:
Batman doesn't kill because at heart he's still a child who believes in right and wrong.
Superman will kill as a last resort (see Doomsday) but will otherwise look for another solution.
Wonder Woman will kill anyone who can't be reasoned with.