this is such a difficult question to answer!
when i was younger, let's say pre-2000, i was totally happy to watch movies on a 32" tv as long as i had a good audio system.
now, i've become accustomed to the projector, and it feels 'wrong' watching movies even on my 64" f8500.
if we talk about bare minimums, then i say both equally. i would not want to watch a movie without at least 5.1 audio, or a 'big screen' hdtv. but if we go from there, i'd rather have a large projection screen than upgrade the audio to 7.1 or better speakers, etc...
but then... i'm WAY more excited about atmos coming out, and i absolutely plan on adopting that. UHD is take it or leave it for me right now.
so i still don't really know how to answer this. i feel like my minimum's for audio are easier to meet than my minimum's for video. and i feel like the quality of equipment i 'need' is much lower for audio(i don't need high speakers, or expensive pre-pro set ups, but i'm totally disappointed in 99% of tv's on the market today, and most projectors too). but at the same time, i feel like the quality of video i have now is so close to perfect, i don't need a better standard, just a display tech that produces black.
i think ultimately, i could get away with less audio though. in my new home i'm planning on doing mostly in-wall speakers to simplify the audio, and clean up the room. and maybe get a larger screen too.
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One