Get the black diamond, when I first looked at poles, I went to REI, and a helpful clerk explaned to me why I should not get the komperdell/rei stuff, both made by same company. He is right. rei/comperdell uses hard cork that does not shape to your hands over time, and he noted, the rei/komper poles have a harsher jarring thing on impact with every plant.
The black diamond trail ergo cork with flick locks are very nice, I'd skip the barrel adjusters, cam flick lock is far more reliable and durable, that mechanism ( a cam with lever) is what holds on almost every decent bicycle wheel in the world, it's solid.
I also agree re length and walking down steep hills, the longer the better. And the steeper, the longer you want. Some people claim to have difficulty walking and adjusting their poles at the same time, and so prefer fixed, but it's really not hard to do with cam flick locks.
I got a friend some used komperdells with a twist adjuster and they are slipping quite badly, didn't notice that at first, hard to fix that problem, with flick locks you tighten a little screw and away you go.
However, bd trail ergo cork was recently on sale online at 50, I got mine for 70 on line. But if you get 20% off, that's about 90 or so, not that far off.