I don't agree that the megapixel myth loses meaning on cell phones. I just think that there's more to it all.
I tend to find that jpeg compression is a detail killer and I recommend using an app that avoids it, such as Camera JB+.
The HTC app is terribly aggressive in that regard and recent updates have addressed a bit of that as well as auto-exposure adjustment.
The only thing that we know about the lens on both phones is that they don't stack up to the Zeiss lens used in the iPhone, but the rest of the components are doing well enough to put them on par with it.
My gripe is with the reviewers.
Lens, sensor, image processing firmware and software all impact details, but they bray like donkeys in their reviews about megapixels, conveniently overlooking the minor difference between the 5 and 8 MP iPhone results.
I think that it's great that both brands are trying to up their game with the cameras.
But there's still room for improvement.
As for splitting hairs on diameter - that's literally true lol.
PS - Last year's One X had about the same size lens (splitting hairs) as this years, 8 MP, F/2.0, yet the SGS3 cleaned up on it with detail - until using a camera app that got rid of their over-compression. I know, I've got last year's HTC and easy access to the SGS3, I've compared them.
Same megapixels, but it was compression that made the detail differences.