Another vote for the G6 from me, I picked up a second-hand one a month or so ago and love it.
In the past I've used an NEX-5N, NEX 6, a Nikon D5200.
I love the detail and the colour of the G6. It's just a proper, solid 1080p image, with a good deal less moire, rolling shutter, softness, than some other cameras I've tried. I found with the other (APSC) cameras I wasn't quite getting that, and I'd end up just taking photos as I wasn't satisfied with the video (tho the D5200 comes in a close second IQ wise. I sold it for the ergonomic issues with video). I haven't tried the latest generation APSC cameras like the D5300 or the A6000 though.
There are a lot of fast (1.7 aperture etc), relatively inexpensive primes for M4/3, so I haven't noticed the low light issues mentioned above. Also, check out this ISO noise test, ISO 640 is very clean:
The ergonomics and feature-set for video on the G6 are the best I've used on a hybrid camera. Last night I just discovered the picture-in-picture manual focus aid (I guess newer Panny bodies like the GX7 and the GH4 would also have this?)