Thank you for providing the short list
Lens filter diameter (larger is better)
HF G30: 58mm
Imaging chip (larger is better)
HF G30: 1/2.84 inch
PJ-790: 1/2.88 inch
Still image resolution:
HF G30: Photo: Approx. 2.91 Megapixels (2136 x 1362)
PJ-790: JPEG: 24.1 Megapixel, 6554 x 3680 (16:9) or 18.1 Megapixel, 4912 x 3680 (4:3)
(The easiest way to understand the camcorder capabilities is to read the specs or the manual - specs are at the end.)
Video recording system:
HF G30: AVCHD or MP4 various standard frame rates and resolutions (all high definition)
PJ-790: AVCHD, MP4 various standard frame rates and resolutions; standard definition
Depends on your requirements.
HF G30: 20x
I think the Canon wins unless the still resolution is that important. I think the surround sound mic is not so useful; neither is the projector - but the night shot is interesting.