The one to get is the "6k" with 1 inch-type sensor. It is BY FAR the better imaging system. The "8k" IMX586 image sensor is NOT a "true" 48mp sensor. Because it's a quad Bayer sensor, it actually has a color filter that is only 12mp. So, you have 48 million photosites that sit under only 12 million color filters. It is "legally" a 48mp sensor. BARELY, yes....but piratically speaking, you can't pass a 48mp quality image through an optical Bayer filter that is only 12mp. So,...this sensor produces and "up-scaled" 48mp image from really 12mp. That quad Bayer design is not there to aid in resolution, it's there to aid in dynamic range. It uses a dual exposure timing algorithm.
Anyway,...the "6k" sensor has a traditional square pixel structure and produces better 5.5k quality video at full sensor width.
CT