I would take something that's in full screen 16x9, one of the many IMAX 3D movies like Grand Canyon Adventure, Arabia, Jerusalem all have decent 3D and well-lit image. Also the full screen will give you a better idea of how the entire screen looks. Can you find a place to demo that 77" still?
Some movies that are full screen or 1.85: Planet of the Apes 2 and it was filmed in 3D, Transformers Age of Extinction (some expanded scenes for IMAX) this one is brightly lit and very colorful, Avatar one of the best demo movies and full screen. Titanic, a conversion but properly done and full screen. Yes, full screen if you haven't noticed by now, the best use of all those pixels not 2.35. That should be the standard for 3D.
There's a bunch of others too the David Attenborough titles, Plants has lots of color throughout, Galapagos.
Just my opinion, if I had to choose between the two I would go with the 77" OLED if that's in your budget. Several reasons why, mostly because it will be harder to get a 3D flat screen later. You could always pick up a projector with 3D later at some point. They'll be easier to buy online because they're smaller and cheaper to ship, not the case with a flat screen. There's obvious reasons why the projector would be better like screen size and such but there really isn't anything that can compete with a flat screen in color and brightness. I love my projector and I love the size but it would be nice to have a flat screen too even if the picture isn't as big. Not to mention this is it for 3D flat panels for the foreseeable future. They're still releasing some 3D projectors.
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