I’ve played with most of the fully ambi lowers on the market and I’ve personally owned two of them.
The absolute best in my opinion is the Radian lower. With that being said, it is horrifically overpriced. But the machining quality is second to none. The tolerances are super tight and every upper I’ve tried it on has had a nice, snug fit. The ADAC is a really clever, effective right side bolt catch and all the other controls are really nice. I especially like the machining and finish quality of the billet parts that are all included. It also comes with the Radian safety which isn’t my favorite but its nice to have in my spare parts collection. I really like how they look but some people think they are really over-styled.
The other lower I’ve had (now sold) is the ADM which is also very nice but I didn’t like the right side bolt lock as much as the Radian and the quality of the small parts wasn’t as nice (cast phosphate coated parts vs the billet nitride parts on the Radian). It also didn’t have as tight of a fit with my uppers. Some people like the fact that the ADM is black anodized vs the Radian’s Cerakote finish. If you insist on having anodizing, buy the ADM. I didn’t care about that because I like to rattle can my guns.
The LMT MARS lower is also very nice. A friend of mine has one and I’ve shot it quite a bit. My only issue with it is that the right side bolt paddle doesn’t fit with the Vltor stripped uppers which I use in many of my uppers. If you prefer the forged, milspec look, this lower is absolutely the way to go. Yes, LMT QC is very hit and miss but they do take care of you if you have a problem.