There are choices where the term “best” is highly relative. This is going to verge into that realm.
I would go with the Daniel Defense Omega rail for simple drop in installation. Its high quality, and gives good value.
If I were going to go with a one piece rail, I would look at the Daniel Defense Lite rail in 10" or 12". I strongly prefer welded rails for strength, so it makes the choice simple for me.
Pinned is going to be stronger, but if you are covering the gas block, its less of an issue. A good gas block can be installed with set screws, but you might want to think about staking the screws as added insurance.
A good rail on a 16" barreled weapon might look something like the below Bravo Company Upper, which us shown wearing a 12" DD Lite rail.