Noveske Forged Flared Lower
If we're delving into the realm of "what if", I would go for the Noveske Forged Flared Lower.
Google it and look at the online images.
It is forged, so superior to billet lowers, despite what the manufacturers of high priced billet lowers would have you believe, and at the same time having many of the features of billet lowers, in addition to being strengthened in a couple of areas.
It is not "ambidextrous", but what does "ambi" mean? Ambi safety and mag release, any lower can be made ambi by easily adding two aftermarket parts. For my money, that would be a BAD 45 degree safety with two short levers (I believe that it the manufacturer recommended option), and Norgon Ambicatch (works well for me, YMMV). That just leaves the bolt release/catch. I'm a lefty, so use my trigger finger to operate the standard one without shifting my grip(I have long fingers), or my left thumb when shooting weak side.
Regards.
Mark