Hey ya'll!
New to this particular diesel forum, spent most of my time on powerstroke boards since thats what I currently own, however a change is in the air and i need some opinions and facts to help me get a nee rig.
Currently I own a 1996 F250 SCLB powerstroke with 250k on the ticker, Ive owned this truck for the last 10yrs and have sunk alot of money into it for performance upgrades and regular and nonregular maintenance. Recently it dawned on me there are better more reliable trucks out there that are crew cabs which i need with the family I have now. Also im now financially able to purchase/finance a nee rig.
As of the 2015 model year im pleased with how the top 3 brands have restyled and outfitted their trucks, on paper and in photos, however I need guidance on the facts and opinions that people can give me on how in real life these trucks work.

On my short list now is:
09-10 F350 crew cab dually
10+ Ram 3500 crew cab dually
08+ GMC 3500 crew cab dually

Im able to finance even a 2015, however id rather get an older truck, save some dough on payments and modify it with the remaining funds to be faster/stronger/better.

The 6.4l gets a bad rap on alot of the forums however it produces some solid numbers with inexpensive fixes to common issues and some inexpensive mods.

The LMM and newer versions I know very little about and that goes the same with the 10+ 6.7l.

What im looking for is a strong solid rig to start with, a clean/well thought out interior, inexpensive fixes to any problem areas, inexpensive modifications to increase power and longevity and finally good MPGs after said modifications.

The inexpensive upgrades ties into the fact I dont want to pour money into a truck like my 7.3l to in the end not see alot of power or also so i dont have to fix some big problem areas such as the E40D trans i basically had to promise my first child for so I could have it rebuilt.

Thanks for any replys!