+1 Black Diamond
Their length adjustment mechanism is the easiest/most secure. I believe Leki is copying it now (the patent expired last year or the year before). It relies on cams to cinch down on the poles instead of expanders inside. Even the good expander-style poles (old Lekis) would gum up after a while and have to be disassembled and cleaned. I used to work at an outdoor shop, so we spent a lot of time selling trekking poles/cleaning them. Never had an issue with the BDs (other than user error).
I have the top of my grip drilled out with a nut epoxied in. I also carry a homemade shooting saddle so I can thread it in and use it as a shooting stick if needed (I only carry a 6" - 9" bipod). It's not quick deploy, since I don't use the poles with the saddle installed, but at the ranges I hunt, it doesn't need to be. I'd rather set up a support and miss the opportunity than try to snap off an offhand shot and wound an animal.