My favorite for prone is the Harris 9-13 swivel, notched leg. I find the 6-9" too short for my body type.

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

Bipods have come a long way in the last few years. I don't have any of the newer stuff to compare with the old school Harris. I'd have to say the newer styles with pic-rail attachment, or M-LOK, would be a lot tougher than the sling-stud mount I'm still using. Probably a significant improvement for especially the big boomers.

That said, I haven't broken a Harris. I shoot 223, 308, 30-06. Nothing too fierce. When I started, Harris was really the only game in town for a decent bipod.