I switched because I broke my HTC One and needed a phone while it was being repaired. I tried the N5, but it was faulty, so got the G2. The replacement HTC was sold to my best mate who wanted one.
The main reason I changed was that the HTC was too easily damaged, even with a case they can dent easily. They are gorgeous devices and i doubt i could have kept it that way, so i switched.
I disagree that the camera on the HTC is worse, its better in many ways, it is much faster, has more features, better exposure, colour balance and per pixel detail than any version of the G2s camera, modded or not. It does take a little more work to get the best out of it though.
The speakers are better on the HTC but i didnt use them. The screen is better to, but smaller.
Overall im happy with the G2, its faster, the larger screen is nice and its not so easily damaged.