My 2 cents worth. A couple of factors are driving sales.
1) Ram interiors across the line are more luxurious. The Silverado is really really nice but the interior design looks like it would have been cutting edge 6 to 7 years ago.
2) Price, price, price! Ram has been offering far better discounts and rebates than GM, Ford, Toyota and Nissan.
3) Ram has a far quieter interior than the others for 2020.
I have owned a variety of GM and Ford trucks over the last 40 years. All have been very good. I bought my first Ram 1500 EcoDiesel in 2017. Manufacturer and dealer discounts played into my buying decision back then($23k off of MSRP or $32,700 for a Laramie Crew Cab 4X4). I could not pass that by.
Fast forward 3 years and 63,000 miles to a couple of weeks ago. I increased the size of my travel trailer thereby needing to increase my tow capacity. I ended up at a small dealership in Placerville, CA. I looked at a new Silverado with the 6.2 gas engine. Nice truck with a dated 6 speed transmission. The best I could due was $6k off of MSRP and a reasonable trade in value of $28k.
I made my way to the Ram dealer. Good discounts on 2020 Laramie Hemi 4x4 trucks with the level 2 trim package, tow package and all. Ended up with a $9k discount from MSRP and a trade in value of $31k on my '17. (Cash talks.)
Again, a no brainer. The 2020 is a nicer, quieter and better performing truck (8speed) that the LTZ Chevy I was looking at. (Although not be much). The deciding factor was the huge price difference.
Price matters....