I have tried POC, sitka, and lam. birch.

Of three woods:
Lamimanted Birch Seems the toughest.
I have broken many POC's
Sitka..is an awesome comprimise between ease of manufacture and toughness.  I lobbed a couple Bunny Buster tipped Sitka's into a 4" diamater cypress log at 10 yards...they still look, feel, and work great!
Anyone try that poplar?

Ramius, Poplar has just about got it all-fairly tough, eay to work, decent weight. The only "downside" is that it is pretty plain-even stained it tends to be rather unremarkable in the looks department.

I like Hickory shafts. I straighten them with the stove method, good heavy durable shaft. What ever material you choose take your time and have fun with it. Try different materials and see what you like the best. One other thing, a good supplier of quality shafting is where you have to start, there is some real junk out there.