Android Central looks at the HTC One Ultrapixel camera vs the GS4:

On the whole, though, the Galaxy S4 produced the better-looking images in our testing, despite its comparative weakness in low light shots. The HTC One's camera is by no means bad, but its performance is clearly weighted towards indoor and low-light photography at the expense of daylight performance. The opposite is true of the Galaxy S4, which excelled in daylight photography, and is backed up by an excellent HDR mode.