AXTS Ambi lower
I am right handed. I hate shooting left handed, but as a man much smarter than me (DH) says "would you rather learn how to do it now, or while getting shot at?" So I practice, but I also can't help but notice that the M4 was not built for left handed people. There are some very fast, very good left handed shooters out there, but they are working against the design of an M4/AR-15 in some ways. The safety, charging handle, bolt release, mag release and even ejection port were made for right handed shooters.
But, thankfully, there is now quite a few options out there for the left handed (eye dominant) folk.
Seekins Precision, note the right site bolt drop button
Full AMBI lower: AXTS
Ambi ejecting upper: Quality Arms
Ambi charging upper: ADCOR Defense (charging handle is forward on the upper - either side), LAR Grizzly (Charges from a handle out of the BCG on either side)
Ambi selector: Too many to mention
ADCOR defense ambi charging upper