My Harris bipod is the 12-25 height. 12 in is right for my prone shooting and the 25 in height works for sitting position. Spouse has the 13.5-27 that works for prone and seated shooting. I would make some shooting sticks like the african hunters use at different heights to see what you need.
We hear lots of good things about other brands too but Harris has worked great for us for 25 years. Not lightweight but mine hardly ever gets taken off of the rifle, I use it in the mountains and on the plains.
The adjustable length legs really come in handy when you have time to adjust them before a shot. I do not prefer the pivoting model but many do really like that feature.