I got an exo pack 2 years ago and loved it compared to my old cabelas day pack for hunting. I picked up a kifaru bikini frame at the beginning of the year and I liked it better due to the larger lumbar pad and that I can adjust the shoulder straps to different heights. I sold the bikini because I didn't like feeling the bag on my back through the frame and just picked up a kifaru tactical frame.
I think the shoulder strap adjustment goes overlooked by most and I'm not sure other companies frames have that ability. With my right shoulder sitting an inch lower than my left that adjustment makes a huge difference in how the pack carries weight at least for me.