No worries Waz, I've got the dodgy hip but unlike the other two I've still got hair :D
Coming at this from a Luthiers point of view, all three are equally important.
Looks. Humans are visual creatures, we like shiney, pretty things...
Playabilty. No brainer there, I think we all agree :)
Tuning stability etc. See last sentence.
No point building a Guitar that hasnt got it all!
DB, some guitars make good cricket bats and firewood too !
You won't even pick up and try a guitar you don't like the look of. There is also an ergonomic thing, how the guitar hangs on your body. I won't play archtop guitars anymore because I find the guitar doesn't hang well on my body and angled back neck leads to shoulder discomfort.
i like how teles look more than strats but ergonomically im impressed everytime i play my strat, the contoured body makes it fit much better
all my guitars are cheap and crappy, so none sound that great, so i guess playability is more important to me really. different ones feel better for playing different stuff though, which is why its important to make sure you have lots of guitars :D