I think you're asking yourself and going back and forth because, though smoother and more appealing in that way, the 2nd image has a certain amount of 'posterization' or uniformity in smaller areas of contrast and color that doesn't look quite right. If that were'nt there but still the noise had been reduced (without sacrificing detail), that would be better, right? And you wouldn't be trying to decide which you liked better. Ideally, noise reduction done right does exactly that.