If I was in your place and had to choose between those 2 camera I would go hands down for the GH4 all day long.
as it more of a production camera with its accessories 10bit 4k out the HDMI etc...
I did a quick hands on test about a mouth ago , and it did impress me at its price point.
But I Still would go for a 5D3 if money is not to big of a issue , as raw at HD resolution is still superior then AVC 8bit 4.2.0 4k
or 10bit uncompressed HD . Just food for thought, I shoot on a 5D2 (Great Camera BTW) and looking to upgrade to 5D3 by the end of this year .