I feel like the series really starts to drag in the middle and should probably have been maybe nine or ten books. I'm curious about what others think. This is what I would do:
Remove the Seanchan entirely (everything about them, not just their POVs)
Remove Valan Luca and the circus stuff
Remove the Kin and probably the Windfinders
Remove most of the camping captive stuff (a lot of this is Shaido)
Trim the Tower novice lessons
Getting rid of the Seanchan alone eliminates or trims a bunch of other character POV chapters where they're dealing with the invasion one way or another, on top of the Seanchan POVs themselves. Besides, being in the minds of slavers is just gross.
It seems like every woman in the series gets captured at least once and spends time as a prisoner in one camp or another, which is just repetitive and excessive. The discovery of new weaves and re-discovery of lost abilities or talents doesn't require a bunch of new POVs. Neither does the quest to find the Bowl of the Winds. And there's too much switching and dishwashing and so on with characters in the White Tower.
There are some pretty annoying Nynaeve POV chapters outside of those bullet points that could go. I also think you could probably get rid of most of the Morgase/Gareth Bryne stuff, and move the rebel Aes Sedai along much more quickly.
I can't fail to note that trimming the books might have allowed RJ to complete the series himself. I'm mainly talking about structural stuff here, not mild annoyances like highly improbable knife throwing, but if you have thoughts on that I'd like to hear them, too. So what would you change to improve the series ("Nothing" is a perfectly valid answer)?