If you're going to do comparisons, at least try to use the same background and framing with each A/B example! The photos with flash seem to be more organic and pleasing to the eye than the ones without. Is it because of the use of flash? I don't think so. I'd try again without flash and get rid of the distracting background. And maybe open up the lens a little more (f/11 on those 2 shots).
Just look at the first flash photo, the center of the watch is pretty close to fitting the 1/3 rule perfectly. They are just much better photographs.