Gimme 60 fps first, better lighting and effects second, more objects on screen third, and resolution last. I definitely realize the benefit of higher res displays but the returns on resolutions over 2K are so, so small comparative to 480 to 1080p.
With 20/20 vision, you have to be within 5 feet of a 40 inch display for 4K to yield benefit over 1080p. You have to be within 3 feet of a 60 inch display to get the full benefit of 4K.
Personally, I would like to up to a 4K projector in a few years, as I can definitely see individual pixels on 1080p within 9 feet from my screen (120 inches).
(640 x 480) 480p is 307200 pixels
(1920 x 1080) 1080p is 2073600 pixels
That is a 6.75 times increase in pixel count going from 480p to 1080p.
(3840 x 2160) 4k is 8294400 pixels.
A 4x increase over 1080p.
(5120 x 2880) 5k is 14745600 pixels.
A 7.1 times increase in pixel count when going from 1080p to 5k.
Clearly, 4k is not as impressive of a jump going from a 480p - 1080p, but it is also much easier to drive.
A more accurate comparison is going from 1080p to 5k, percentage scaling wise.