I've owned both gas & diesel powered HD trucks, using them as towing vehicles and road warriors on long trips.
Here's what I've learned:
Diesel trucks generally cost more to purchase than a comparably equipped gas engine truck.
Diesel powered trucks move heavy loads from a dead stop better than gas powered rigs due to the available torque.
Diesel powered trucks generally get better loaded & unloaded fuel mileage.
Diesel fuel, at this moment in my area, is generally cheaper than mid-grade & premium gasoline. YMMV
Diesel engines do cost a bit more to maintain & repair vs. a gasoline engine especially with the fuel and engine lubrication systems.
Diesel trucks can be oily, smelly and if you do your own maintenance you have to prepare for that.
A deleted truck may, or may not, be illegal in your area.
Diesel trucks have a lower payload capacity than their gas-powered peers due to the additional weight of the diesel engine and associated equipment. Remember that payload includes tongue weight or pin weight depending on what type of trailer you are towing.
There is nothing that will bring a grin to my face faster than a WOT run in a fully deleted, tuned, diesel truck. A gas powered HD, with the right mods, can be a lot of fun as well.
Deleting and tuning a diesel truck used to be a fairly easy thing to do. With more stringent regulations & state-level DEQ/EPA enforcement actions many shops no longer sell the parts, tuners and services needed to make those performance modifications. This may not be the case in your area (it was in mine after I deleted & tuned my CTD) but it may be worth your time to research the regulations, read up on emissions testing that may be required and talk to some local shops.
It may be much easier, and cheaper, to modify a gas powered HD truck these days. I added a cold air intake, programmer, custom tune & freer flowing exhaust to my 6.4L powered HD Ram. That truck was a real performer after those mods were done. But it would not turn over the rear wheels at 60 MPH on the freeway when shifting down and hammering the throttle like my CTD could.
So there are pros and cons to each type truck. Give some consideration to how you will generally use the truck, how heavy you will be towing and how much you are willing to spend to purchase and maintain the truck.
Gas vs. Diesel:
Performance:
2014 6.4L WOT
6.7L CTD Cold Start
Deleted 6.7L CTD
Of course, if you want more specifics on the delete and tune parts then PM me and I'll fill you in on what I used.
Good luck with your choices.