I replaced a G9 with a G16 a year ago. I needed something that was strictly grab-n-go, was affordable, and wasn't going to cause a lot of angst if it got damaged or stolen. The G16 has full manual controls, and was/is priced to be affordable. At $500, it's $150-$300 less than the G7 X, G1 X, and G1 X Mk II.
The G16 is a great little camera. For stills, it can go to ISO 6400. Beyond that, IQ is terrible. Fwiw, I push my 5DM3 hard and occasionally go to ISO 25,600, so pushing ISO isn't a problem for me. If the camera can do it, great. The G16 is good only to ISO 6400.
The effective focal length is 28-140mm, which is quite good. I've used it a couple times in NYC and once at Walt Disney World.
NYC: http://grahamglover.zenfolio.com/p207192676
WDW: http://grahamglover.zenfolio.com/p152617886
For video, I generally don't know anything about it. That said, the G16 can do HD video. The G16 has twin microphones built into the top of the camera. They're sufficiently good that they can provide stereo separation, and the quality is quite acceptable, given this is a simple camera. How well it handles wind noise I have no idea.
NOTE: No matter what you get for a G camera, you may find your G camera will coddle you beyond what you want. For instance, the G16 allows manual focus, as did its predecessor in my home, the G9. With the G9, if you messed up focus, you messed up focus. I have no problem with that. With the G16, if it thinks you messed up focus, it will automatically refocus for you. This is not amusing in the slightest. If I'm on manual focus, I expect the camera to be on that - manual focus. This coddle "feature" can be turned off, but by default it is turned on. Whether this is on the other G cameras I don't know, but being PowerShot cameras I suspect they may be.
For me, the bottom line is the G16 is a great little travel camera that can take the place of my 5DM3 when needed. The price is right for me, the capabilities are what I need for the things and places I shoot, and I have never regretted getting this over the other Gs.
Good luck! Hope this helps.