Here is my opinion. I owned two 97 Chevy 6.5's, one 2500 & the other a 3500. Both were bought new with 4x4, Auto's. Great trucks owned both till around the 200,000 mark. Both had injector pumps replaced around the 120,000 mile mark. 2500 tranny made it to 140,000 and the 3500 to 190,000 miles. Both had 8' plows on the front ends and were used for landscaping. They pulled dailey 14 to 16k worth of skidsteer, 32' gooseneck, brick pavers, balled trees and not once did I have front end problems. They both drove great when I sold them. Other than hard starting in the winter and being a little weak for towing power they were great trucks. I wouldn't hesitate to own another.
I've owned every style of 5.9 Cummins from a Ve, P-Pump, VP-44, Cp3 injected including one 6.7. Great motor and for towing on a regular basis (I have a Hotshoting & Trucking company) there is no doubt in my mind this is the best engine for service life, maintenance cost & fuel mileage. I've ran them to well over 350,000 miles grossing 30k on a regular basis. Although the Dodge has a lack luster interior and rides the worst of all three its a truck. If you like to tweak the power they are super easy to do so and are rock solid reliable with a manual tranny (never had much luck with the auto's).
I have only owned one Ford IDI (which I have currently). I've owned every 7.3 for the IDI to the OBS to the Super Duty and all I can say is they are great all around motors. It's comparable to the 6.5 Chevy for power, however I love Ford interiors. They are cheap to repair, the build quality seems to be on par or better than Chevy (Dodge is a complete last in this area). The Ford suspensions seem to carry a load better than a Chevy and equal the Dodge. My Ford has zero rattles and for being 18 years old I think that's impressive for how much plowing it has seen. My IDI has been in the family since new and I will say it has had the most front end repair work of all the trucks I've owned. But to its defense its had a 925# V-blade plow on it since it was 3 days old which out weighs my next closest plow by 125#'s (not to mention it has the D50 TTB). At 120,000 it is seeing a full fuel system overhaul, mostly because its just time and has never left anyone stranded. It starts in the cold pretty good compared to my 6.5's but not as well as any of my Cummins did (but it does start which is the important thing).
If I had my choice for a older truck it would be a 92 to 97 F350 4x4 Crew Cab Short Box with a P-pumped 12V 5.9 Cummins and a built E40D auto (350hp & 650 Ft lbs at the wheels). It would be good on fuel, could pull pretty much what I need and would be easy to drive for the wife. I plan to build this exact truck this winter instead of buying another new truck with all the emissions garbage. Plus for $15k and my labor I can have a killer truck.
As stated before, all makes of trucks have there good & bad. As long as its made in America does it really matter what brand truck you drive as long as your happy?