Each to their own.
Personally I like the Gh4's colors, but it took me a while to get the settings I like.
Basically it reproduces pretty much exactly what my eyes see, in terms of detail and colors...and I like that, my eyes are the ultimate judge and I cant trade them in on next years model, I have relied on them for years in graphic art and 3d design.
Using iDynamic in reasonable light gives good detail in shadows with practically no noise or blotching that I can see.
I had a Canon 60D, my son uses it these days for surf videos...I cant say the same about that, its a nice enough image, but to my eyes (and many others, its nowhere near the class of the GH4 in practically any area).
Many users have sold their 5DMk3's and many others are able to match the color nicely to the Canon C100, there are tons of threads on dvxuser.com about this.
But at the end of the day, the whole GH4 Vs Canon Vs Nikon Micro 4/3rd vs Full Frame...is a lot like the argument that has been around for decades in relation to guitars...
is a single coil better than a humbucker? (they are certainly different) or is a Fender (largely single coils) better than a Gibson (largely Humbuckers)? or does and Ibanez lack soul (now theres a word that puts the argument out of reach LOL!!...the camera equivalent is the much maligned term "filmic")
At the end of the day, its horses for courses, I personally dont base my decisions on anyones Sony, Canon, Nikon, Panasonic preferences or bias...I use what pleases me...and I'll bet most others do the same.