I can’t comment much on a gas as we have always had diesel trucks, mostly 3500 duallys (diesel) for the past 20 years.
Back in 2018 we did have a Chevy 3500 and I was looking at getting a 2500 diesel for myself, and the prices were pretty much the same - within a few thousand dollars. Almost wasn’t worth it to go with a 2500, but not sure if the prices are still so close now as I haven’t looked since 2018.
Our 2018 was a great truck and we used it to tow our 52’ horse trailer with LQ. The weight was 24,000lb and it towed like a beast. Now my husband is all into interiors and when Dodge came out with the Longhorn addition in 2019, he traded in his High Country for it. The first time he towed with the Dodge he called the dealership as he thought something was wrong with it. It did not tow like the Chevy at all. The Dodge lagged and had a hard time keeping up with speed etc. Long story short, gearing makes the difference. The Chevy (GM) has a different gearing ratio and it made all the difference in hauling such a big trailer.
We still have the Dodge, my husband is a contractor as well and he uses it to tow his tool trailer to jobs on a daily basis. We have added a Freightliner and it tows with 0 issues (and just had the interior redone as he did not like the Sport Chassis interior it came with. I must say its quite nice and one of a kind now!).
Just my thoughts on a Chevy/GM. This is coming from an almost exclusive Dodge household here. My hubby was very impressed with his Chevy and my mother in law has a 3500 dually GM Denali and loves it to death. She tows a large RV and a large Toy Hauler in the past with it with 0 issues. She also had a Dodge and traded it in within a year of owning it as she didn’t like the way it handled.
Both trucks are also used to just drive around without hauling They are not great on fuel. They pretty much burn the same if driven around town or if its hauling a trailer. It averages around 22-25L/100km.
all of our trucks have been diesel. We tow a lot (horse trailers - 2 horse, 2 +1 and our 52’ beast, shop trailers - over 10,000lbs, dump trailers, you name it - pretty much on the daily) and it wasn’t worth it to get a gas