2020 Ram 1500 Bighorn trim with the 3.6L V6, 8 speed transmission and 2wd. I have around 46K miles on this truck.
There are numerous great things about this truck. The ride quality is terrific. The interior is very nice, it feels quality even though it's only the mid tier level trim. It is a very comfortable and extremely quiet place to be. The engine, while lacking that low end V8 torque has good power for day to day driving. I haven't towed a lot with it but did take a 16' car trailer on a 6 hr trip and it had plenty of power for that trip. The chassis and brakes felt more than capable for that as well.
So far it's been extremely reliable. Not a single issue to report. No costs aside from oil changes. Even the factory tires are only half worn. I don't spend the time to calculate mpgs by hand but the lifetime average from the display is 22.5 MPG.
2021 GMC Sierra 1500 Base trim with the 5.3L V8 and 6 speed transmission. 4wd with the single speed transfer case. I only have about 2300 miles on this one.
This is a base model truck so the interior is plain. It has rubber floor coverings instead of carpet. Even considering the differences in the trim level this interior feels less quality. The materials don't feel like they will last. The center console lid squeaks like crazy and it's loud inside. On the plus side the seats are very supportive and I have yet to get uncomfortable in them. With the Ram I'm squirming after about three hours. I haven't had the opportunity to tow with it yet but the V8 has plenty of power and torque.
Too early to tell about the reliability but I have a sneaking suspicion it's going to be a little needier the the Ram has proven to be. This truck does not have the troublesome AFM system installed but I've read that the lifters can still be an issue. So far I'm averaging 18 MPG.
It's a little unfair to compare these two trucks directly because they are spec'd for two different purposes but I have noticed some differences.
The brakes in the Ram have more stopping power and better initial bite. After switching into the GMC from driving the Ram I find myself coming in hot quite a bit until I adjust how much force to put into the brake pedal.
The suspension of the Ram feels way more sorted. The shocks on GMC feel way under damped even being brand new and the Ram having so many miles it's not even comparable. They both are comfortable but the Ram has a significant edge.
It's really incredible how much better the Ram moves through the air. Ram spent a lot of time working on aerodynamics when they designed the 5th gen trucks and it shows. It's way more stable at highway speeds. Way more resistant to cross winds and way more quiet.
The infotainment systems operate very similarly with about the same reaction times. The rear camera on the Ram is better.
I would without question recommend a 5th gen Ram based on my ownership experience. It's really been excellent. Having said all that I will probably be selling it because I don't need two trucks and I looked for so long to find a black single cab 8' bed 4x4 GMC, it has that certain intangible quality that the Ram just doesn't have.