I have all of the displays mentioned in this thread - I am running out of places to move them to! Now, 55 LG E7 oled in bedroom, Panasonic 50 VT 20 in office, and Panasonic 65 ZT 60 as main display in home theater. Initially, while I love the absolute blacks on the E7, I was slightly underwhelmed to be honest. There is a richness and "organicness" to the plasma picture that oled does not have - it looks more "digitized", though not as bad as LED/LCD, and the motion is not as smooth. My wife (who is no videophile) asked if I could bring the VT 20 back into the bedroom as she preferred the picture, rising blacks and all. I refused, and fortunately LG came out with the Technicolor firmware update, which substantially improved the picture, colors were richer, everything just looked better. The Dolby Vision demos are pretty spectacular too, so I am content now that I feel the E7 was an upgrade over the VT 20, except in motion handling, and maybe still in the naturalness of the image.
As to the ZT 60 vs. the E7, even with 4K, HDR, and perfect blacks, I am not sure that I prefer the oled to the plasma overall. With just a small amount of ambient light (which is how I like to watch movies), the ZT 60 blacks are indistinguishable from the oled. The picture on the ZT is just a little more natural and rich, and the motion handling is better. And I still enjoy a 3D movie, which is no longer available on oled.
Lastly, I got an HD Fury Linker to be able to play the 4K streams from my Roku Premeire Plus (which have Atmos audio). I got it for the Atmos audio, but I was really surprised how good 4K content downscaled by the Linker looked on my ZT 60. I think it has something to do with 444 Chroma Sub-Sampling, but 4K content on my 1080P ZT 60 looks spectacular - it really looks 4K! And the ZT 60 is capable of 98% coverage of the P3 color space so on wide color gamut 4K material I can have the Linker send rec 2020 color to the ZT 60 for more "pop" in the colors.