Lumix GH4. It's now available at a number of outlets for approximately $1,200 (body only), down $300 from its list price of $1,500. B&H has gone one better and is offering a $150 gift card with purchase. Since a B&H gift card is as good as cash to a photographer, this effectively lowers the camera's price to only $1,050.
No price has been set yet for the GH5, but best estimates are that it will be around $1,600, only slightly more expensive than the GH4's regular price. The GH5 should be a ground breaking camera for video enthusiasts as it will offer a revolutionary 6K video. It will also offer incremental improvements for still photography - one stop better performance in low light and 24mpx rather than the current 16mpx. These are wonderful enhancements, but since I don't regularly shoot video and invariably use my Nikon Df for low light photography, they weren't that important to me. On the other hand, paying effectively $1,050 for the GH4 instead of $1,600 for the GH5 represents a savings of roughly 35%, and that's a big number.
I decided to go with the GH4 primarily because it's not what I regard as a professional camera, like my Nikons. The Panasonic is really my "carry around" camera that I use for street shooting and travel photography. As such, the GH4 is plenty good enough for my purposes. Another factor that influenced my decision is that the Panasonic line, no matter what its reps may say, is really designed as a consumer camera. It's simply not built to be as durable as a top of the line Nikon. I purchased the GH2 in 2011 and used it for five years before I began to experience problems with it. The camera "grip" that holds the lens is losing tension and the electronics sometimes act up, e.g., I keep being asked to set to set ISO or white balance. I'm not complaining - I feel I got good use out of the GH2 - but obviously I don't want to pour too much money into a camera with a limited lifetime, especially one that's intended for casual use.
In the end, after a great deal of consideration, I purchased the GH4 to replace my ailing GH2 and have been shooting with it for over a week now. I've been very happy with the results - the photos are quite similar to those I obtained with the GH2, which were excellent. The only problem I've had with the GH4 is that the user manual is too basic and leaves out essential information, e.g. it's now necessary to check the camera's screen and make a choice when downloading photos via the USB connection. This was minor, though, and the problem was soon solved via live chat when I contacted Panasonic support.