1. "No accurate and useful information has ever been given by detainees while being tortured." No one, except for the shallowest, self-satisfied strawman builder would give the statement this possible meaning.
2. "The value of useful information given during torture is hidden and overwhelmed by the false information and false leads given during the detainees' attempt to stop the torture." Some people believe this; I don't know whether it's true.
3. Variation on number 2 above, adding "the torture prevents opportunities for rapport-building techniques that get better-quality information with fewer false leads." I think this is what expert interrogators actually believe. I suspect they're right except for the never-happened hypothetical ticking nuclear bomb situation (one other possible exception: during actual combat, where capturing an enemy soldier in the middle of a firefight could give very useful information).
4. Variation on number 2 above, adding "the interrogators are are also likely to believe the false information given by the detainee because the detainee is seeking to give the response that the interrogator wants to hear." I think this is what happened with a number of detainees who were willing to say Al Qaeda was tied to Saddam, and the interrogators actually believed it.
5. "The value of any good intel from torture is far outweighed by the harm done to the effort to win hearts and minds and separate the terrorists from public support." This is an independent reason that complements numbers 2 through 4 above and is the one that settles it, in my opinion. Of course, right wingers and the faux moderates who position themselves on interrogations could care less about what is the actual road to victory.
A tangent about additional rightwing nonsense: in discussing the National Review's current semi-defense of its 1964 opposition to civil rights, WF Buckley's alleged renunciation of prior racist views came up in the comments. I wrote a follow-up comment saying that I find much mention of his renunciation, but no actual quotes. If anyone's seen where Buckley comes clean, I'd like to know.