I have an Accu-Tac and it is the most stable bipod I have tried probably because of their size and weight and they are built tough, they are perfect for bench rest shooting, zero flex. I purchased 4 sets of leg extensions so it almost works like a medium height tripod, great for field shooting but it is again heavy. I have a few smaller lighter bipods but they don't get used, the Accu-Tac is that much better. If you have heavy airguns then an Accu-Tac is a great choice, I shoot a Taipan Vet2 8lbs unscoped and a RAW Chassis HMx LRT over 7lbs unscoped, both are heavy.
Another vote for the Accutac. Very sturdy and solid. I have it on my Raw HM 1000x chassis rifle and it’s great. I had a cheap Caldwell bipod to start with and then moved to the Accutac. No comparison!
Comparatively priced to atlas, heavier, great for benchrest, especially with 30 cal. But atlas has advantage with lighter weight when carrying gun afield. Once I tasted accu tac, bought 6, never looked back.