I'm a fan of the Harris bipod. The look alike imports are not of the same quality of materials and it tells w/ constant or rough use. For occasional sport shoot they might be OK.
I think a swivel model adds cost, but offers an essential advantage of being able to level the rifle. I do not like the notched legs, but many do.
Height? 6-9" is lower and more stable, as well as lighter if you leave it on the rifle. But 9-13" might get you over an obstruction that the shorty would not.
The mother of all bipods is the Sinclair F-class, which costs 2-3x more than a Harris, and is not very portable, but is akin to a bench you lay behind.
Hold'em and squeez'em