Hmm. I did the math and if you land a W->Q combo @ lvl 5, you have the same damage at 50 AP if you have rank 3 W and rank 1 Q as you do with rank 3 Q and rank 1 W. Makes sense since both spells scale at the same rate (+40 dmg per rank), so really the only benefit of leveling W is to use it in combo to harass more often and the added slow for escapes. On the other hand, not leveling W will give a cheaper up front cost to attempt harassing and you don't have to commit until you land the W, and make you more useful in team fights when you can land multiple Qs in short succession.
Conclusion: Going to level Q first over W, but still harass with W and be sure to follow up with a Q when they hit. Harassing with Q is still kinda risky since even when you land it there's no stopping them from trading back just as hard and is probably better used to focus on farming and clearing creep waves. Until the patch though, W still has a better rank 1 than Q, so until then I'll still probably go W->Q->E or W->Q->Q for levels 1-3.
