I just got a Ram 3500 DRW Mega Longhorn Limited. I love it. Cummins/Aisin 4wd. It has about all the bell & whistles (no sunroof). I came up from a Ford F250 V10 gasser.
Some say my truck looks funny with the front being longer than the bed, oh well. I can drop the back seat and lay down fairly comfortably and I have a ton of room behind the seat. Cargo cam, back-up cam, shift on the fly, four down flat tow capability(6 in my case) but remember, MAKE SURE IT HAS WHAT YOU NEED/WANT WHEN YOU GET IT! 'Cuz plug and play ain't there for most upgrades. I ordered mine from a high volume dealer in another state during a month with high $rebates and my companies affiliate discount. It took 7 weeks from placing the order to delivery (yours may vary)
The solid thunk when you close the doors is because of the double/triple seals ( I used to yell at DW for slamming the doors on the old truck, with the Ram it's the only way to make sure they latch). The new Cummins is QUIET! I just got my Reese picture frame in from Croft, cheapest and one of the few that had them in stock. But I banged up my shoulder and can't put it in yet. The bed rails are taller( mine are 59") My 5er is an older one and I will probably have to flip the axles and add spacers to make it level. I have read a few posts about the pin box hitting the rails without the Rambox, might have to do with the length/height of the pin box.
Get out and drive the type of truck you are interested in. Go to the corporate site and 'Build and Price" the truck you want. Find what add ons drop others, what is in a certain trim level. A lot of dealers have an Internet Sales Dept. Go to Brand forums and read what's going on the the new models.
I went to a local Ram dealer and drove a 3500 DRW CC LB, got to have it for an afternoon. Drove it on back roads, city streets and the freeway. Then I took it home, picked up the wife and had her drive it. It wasn't a Mega, but it was close. It was as close as I could get. She liked it. We spent months researching. Priced it against the other brands with the options as close as we could get.
NOTE: I don't like the GM's external looks(haven't for several years) and the Ford's were getting there. I went with the DRW as I plan to move up to a bigger 5er in a few years and as I tend to keep my vehicles for awhile, might as well get enough to meet my planned upgrades.
I love my truck but, I only have 2k on it and none towing so far.
Make a "Must have" list, a "would like" list and a list of what you might want "aftermarket" list and see how/if they combine.
Oh yeah, these trucks aren't cheap!