I have or have had:
'09 RAM 1500 with Hemi/3.92 and moonroof, regular tailgate, no RamBoxes - 193K miles
'19 RAM 1500 with Hemi/eTorque/3.92, no sunroof, regular tailgate, RamBoxes - 72K miles
'21 RAM 1500 with EcoDiesel/3.21, Pano sunroof, MFT, RamBoxes - 30K miles, so far
I would not get a sunroof. I only have one now because I found this truck used and it had it. I don't use it and it's just something to break and/or leak, and to let the truck get hotter inside. I never used the one in my '09, either, and I didn't miss it when I didn't have one in my '19 for the 3 years that I had that truck.
I LOVE the Multi-Function Tailgate. That, the diesel, and the 3.21 diff were the main reasons I traded my '19 for this '21.
I very rarely carry anything in my truck that requires the tailgate to stay down while driving. Which means I very rarely have any need for the tailgate to open in the "classic" way. All the rest of the time - i.e. 99% - having it open barn door style just makes it so much easier to take stuff out and put stuff in.
My only gripe with the MFT is that the truck has a drop-down step at the back for getting in/out with the gate open barn door style. But, it does not have a drop-down step (like my '19 did) for climbing in/out with the tailgate dropped down "classic" style. And, apparently, I cannot just bolt on the Mopar one that they have for trucks with classic tailgates. When I DO have the tailgate open classic-style, it is really annoying to not have a step to help my old azz get up in there.
If you get the MFT and you do NOT get RamBoxes, then your bed will have braces in the front corners that interfere with installing some tonneau covers. If you DO get RamBoxes, then the rest of the bed is the same whether you have a MFT or not. Meaning, any cover that fits with RamBoxes will fit whether you have the MFT or not. Side note: The Mopar trifold soft cover sucks BIG time. The Bak Revolver X4s has a fitment for RamBoxes (with or without MFT) and it is an awesome cover.
I love my RamBoxes. I'm pretty OCD, but I'm not as OCD as some people on here. The "not-perfect-ness" of my RamBoxes on my '19 and on my '21 doesn't bother me. They are way too useful to not get them because of a little bit of warping that MAY occur.
I also really like the air suspension and the power running boards. Lowering the truck to Entry/Exit height and having those big boards swing out is what makes it feasible for my 78 year old, 280# father to comfortably get in and out of my truck. Lowering it to Entry/Exit height also makes it noticeably easier and more comfortable for me to load heavy stuff (like scuba tanks, including twinsets) in and out of the bed.
The air suspension has also been helpful a couple of times when trying to hook up to trailers. Mainly when the trailer tongue is too low because its jack has sunk into wet ground. I lower the whole truck to get under it, then lift it back up.
With a 3.92 rear end, the truck turns 2200 RPMs at 80 MPH. With a 3.21, it turns 1800 RPMs. I do a lot of highway driving, running at 10 MPH over the limit. I.e. a lot of miles at 80 MPH.
I do not miss anything about having a 3.92 rear end. I am very glad to have the 3.21. With an 8-speed tranny, even with a 3.21 diff, 1st gear is still plenty low enough to get any trailer moving that is within the truck's weight specs. If were towing heavy enough and often enough to think I actually needed 3.92 gears, I would get a 2500 with a Cummins.