Popular Mechanics did a shootout where none of their staff could pick the difference between any of the cables used.
Choice, a respected Australian consumer reviews organisation, did an HDMI cable comparison, slamming the expensive ones as rip-offs:
Is dearer better?
No. Our testing found no statistically significant variations in score either for picture or sound. Although the results were slightly in favour of the more expensive brand for longer lengths, the differences were not enough to conclude any brand delivers a significantly better result.
Unless you need a shielded cable (you're running it in your wall cavity near AC power, or for runs of 50+ feet) the generic cable will perform identically to an expensive one (emphasis mine):
For longer cables over 10 metres, differences in performance may possibly be an issue if there is significant interference between the video source and display, but we did not find any difference until lengths were combined to form lengths more than 33 metres.