OK so it varies a bit.
Q is huge for wave control, and csing it makes up for your slow attack speed and helps you stop yourself from getting pushed under tower. it also has pretty nice damage after a couple ranks. (if your maxing it first you can see it killing 3 minions than chunking an opponent nicely)
In general max it first.
W is great for the snare combo potential with teammates in general max it second.
Now i'm saying max it first but that's not necessarily "all points into q, all points into w" etc...
I like to have two points in both W and Q by level 6. The extra .25 snare duration on the W can be huge for securing kills. Its power also varies on what your allies have to help you proc it.
I guess what i'm trying to say is max Q first but do not be afraid to put extra early points in W, depending on whose on your team / enemy team the extra root duration value can be awesome.
Both are debatable for starting as well. Hands down W is better for invades one way or another because CC. Or even an aggressive level 1 play, Q is better for the early cs, taking control of the wave and trying to hit 2 first.