Which is best among Lumix GX8, GH4, Sony a6300, Nikon D7200, D5500, Canon 80D, 760D?

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I want to buy camera out of Lumix GX8, GH4, Sony a6300, Nikon D7200, D5500, Canon 80D, 760D
Which are offering following thing:

Color range red looks more red rather than fainted red color
Best in continuous Auto focus while taking Video
4K without cropping sensor
Huge buffer
No heat problem
More lens option and all on very less price compare to other brands
Fast ISO auto change when suddenly moving from low light place to high light place while talking video.

* Color range red looks more red rather than fainted red color -- you need to be willing to shoot in RAW and process your images in Lightroom
* Best in continuous Auto focus while taking Video -- If you are shooting from a script, using manual, follow focus is what the motion picture companies have been doing for decades. Hoping that a camera will follow focus automatically is not very realistic
* 4K without cropping sensor -- you may want to look into buying a Black Magic 4/3 video camera
* Huge buffer -- what you need is a camera that uses super fast XQD or CFast memory cards or shoot RAW video and record it using a device like the Ninja 2 and SSD drive directly from the cameras HDMI port
* No heat problem -- All cameras using CMOS sensors are going the have heat problems.
* More lens option -- The video cameras NOT digital SLR cameras) with the most lens options for shooting video are the ones with PL, 4/3 and EF mounts and
* all on very less price compare to other brands -- good glass and camera gear is expensive.
* Fast ISO auto change when suddenly moving from low light place to highlight place while talking video - This requirement shows you have NO experience shooting film or video from a script. The key to high quality film or video is keeping the ISO of the film or sensor at 100 ISO to assure that each scene has the same quality image as all the others. When making cuts in post, it can be very jarring to the viewer when a cut is from a realitivly noise free video sequence to one with huge amouts of noise because the director chose to use a high ISO rather than to light the scene correctly.

Here is a link that shows you how directors of motion pictures assure continuity of colour, dynamic range and noiseless or grainless scenes

You may want to talk to your film advisor about all these issues you seem to want to correct by just buying the "right" camera. Such a camera does NOT exist.

Shooting videos and motion pictures is a very expensive proposition, so do not expect to produce amazing video on the "cheap"

80D would be the winner with anything from Nikon being at the bottom due to the horrible AF when making videos, not to mention that the only Nikon with 4K is the new $6,500 D5. Reviewers of the D5 say that it, along with all Nikon DSLRs, are horrible for video.

It would be close call between the Canon 80D, Sony A6300, and the GH4. Personally, I'd go with either the 80D or the A6300 due to the larger sensor vs the Micro 4/3 sensor in the GH4. Check youtube for comparisons.

Why isn't there a Pentax on your list?

Looks like you're looking for a camera for filming.

I suggest that you look at the Blackmagic cinema camera instead. It will provide you the features you need to shoot excellent video for your intended purpose.

With respect to "color range" that's done in post processing, it is not a feature of the camera itself.

To get the red that you want, nail exposure perfectly in-camera or tweak saturation in the computer. The higher-end the camera model is, the less tweaking you will need to do so expect best results with the 80D and D750. DSLRs have more lens options.

With AF and video, the mirrorless cameras will do better especially in lower lighting conditions.