Theres not much to discuss,
staking and enslaving innocent people = purely evil
trying to set up some kind of stable and fair society = not evil (especially president Tandy has a very good reputation), though im not sure what the new president kimba is up too
As Gabriel said, if you want to remain focused on only those two things, then congratulations. You are missing the forest, sunrise, and waterfall for the twig.
For there to be peace, there must be brutality. There must be clear and drastic consequences to breaking the peace. For one who values peace over "freedom", the Legion is the heroic faction.
For there to be democracy, you cannot have brutality. Thus there will be little perceived consequence to breaking the peace. The one thing democracy allows in return for this is "freedom".
For there to be progress, there must be thought. "There is no greater evil than ignorance." Talk to Caesar, Mr. House, or pick your own brain and the thought is apparent. From where the knowledge comes and to whence it is going is clear. The closest thing you get to an evaluation of the NCR is from Marcus & Ulysses, decidedly not in the NCR.
This is actually an extreme simplification of the debate, but it illustrates what the factions provide.
You want peace? Legion is the faction who can answer this call and explain what they're going to do with it.
You want "freedom"? NCR is the only faction who can provide this, but you'll get a blank stare if you ask "Then what?"
You want progress? House is the clear choice.
-Nukeknockout