Best M&P 2.0 9mm aftermarket barrel?

[Tony Pic]

I don't have the M&P like you, I have the Shield and I put a Silencerco threaded barrel on it and it shoots better than the factory one. Drop in with fitting. The same with my 92f Silcenerco bbl. No fitting.

https://silencerco.com/threaded-barrel.html

Midway has a good supply of threaded barrels for your pistol also.

https://www.midwayusa.com/product/2120154761

[H-D]

I've tried a few barrels over the years (Glock though)...and by far the best fitting and most accurate I have used is KKM. That "button rifling" he spins on them is what sets them apart IMO.