what do i max for irelia

R > W > E > Q

R cause it's your ulti, obviously.

W for sustain/true damage - you can't argue with true damage hurting like a mofo.

E and Q provide more utility than anything, however E provides a sufficiently large amount more damage (I believe it's double Q's base damage at max rank) while only scaling with AP, and provides a slow/stun.

Q scales with AD, but that isn't the point here, the point is that it's a gap close with a reset. Treat it like Katarina's Shunpo - max last.

Your max order won't change for almost any situation and shouldn't be what you focus on - change your playstyle to adapt to the lane.

E and W both viable maxes. E is safer, W does more damage. E sets up ganks and teamfights better. If you need sustain, W. If you need to not get all-in'd, E. If you want to kill them over and over by yourself, W.