If the question had been murder vs. rape, I would've said murder. But killing in general?
Like coolestguyever said, killing has a ton of variables: Who, by whom, how, why etc. Ie. stalking and killing a child in cold blood would be universally considered to be completely reprehensible, while gunning down a brutal dictator would probably be accepted, even lauded by some people. Death penalty (essentially government-sanctioned murder IMO) is still considered a valid form of punishment, and I don't think any regime has a "rape-penalty" for any crime. Also, IIRC, killings tend to carry much higher sentences than rapes do.
Another thing to consider is that killing is final, while a rape victim can still recover from both the mental and physical damage. On the other hand, rape can also be considered as a form of torture, and in the case of rape, the suffering can last for a lifetime.
...
If I personally had to choose between getting killed or raped, I'd take the latter option. As for which one is worse:
I'll just say that both killing and raping suck immensely and leave it at that.
Warning: The preceding message may or may not have included sarcasm, cynicism, irony, full stops, commas, slashes, words, letters, sentences, lines, quotes, flaeed gramar, cryptic metaphors or other means of annoying communication. Viewer discretion is/was strongly advised.
