Alright, I'll bite on this. I've never owned a Duramax, but I have owned two Cummins (24v and 3rd gen 5.9), as well as my 6.0 Powerstroke. ALL have their issues. The Duramax was prone to intake issues and overheating. The 24v 5.9 Cummins had fuel pump issues, which led to failed injector pumps, and it also had APPS (Auxiliary Pedal Position Sensor) problems....I experienced both failures on my '01; I replaced the original POS Carter fuel pump with a PureFlow Air Dog frame-mounted pump. The biggest issue the 24v suffered from was the cursed "53" block cracks. The 3rd gen 5.9 had CP3 pump issues. That said, I loved both my '01 and '05 Rams.
The biggest drawback to the Chevy and Dodge is the lack of room in the rear passenger area. This is where Ford shines. The 6.0's Achilles heal was the casting sand left in the blocks, in addition to the Ford Gold coolant, which contains silicates. The oil cooler would get clogged, impeding coolant to flow to the EGR cooler, which caused the solder to melt and allow coolant to flow into the heads, hydrolocking the engine. Ford's desire to win the hp/torque peeing contest led to their request of IH to max out the VT365's capabilities.
The class-action lawsuit brought on by ambulance companies who experienced catastrophic failure of their 6.0 engines is what led IH to sever ties with Ford, after they attempted to blame IH for the failures. Ford asked IH to pay and were promptly told to go pound sand.
The fix to the 6.0 is easy and does not cost thousands (sorry, REDNAX, but I respectfully disagree with you on this....what I recommend is not legal, so I assume no responsibility for the advice I give):
1) Get rid of the EGR and EGR cooler and purchase a bypass system...prices average around $400 for the kits.
2) Add a coolant filter.....price is about $160.....IH runs them on the VT365 (the sister engine to the 6.0)
3) Flush the hell out of the engine and replace with an Extended Life Coolant....I use Fleetrite, but there is also Cat and a few others.
4) Gut the catalytic converter.
5) and MOST important........DO NOT CHIP THE 6.0!!!!!!!! The heads are attached to the block with Torque To Yield (TTY) bolts and will stretch. They can NOT take the extra HP and torque.
I have done the above and have had ZERO issues with my 6.0
If people are uncomfortable with breaking emissions laws, they can still install a coolant filter and replace the EGR cooler with a Bulletproof EGR cooler (Google it), flush the engine thoroughly and replace with ELC.
My personal favorite truck would be a Ford body with a Cummins engine and an Allison transmission, but I don't have the $25,000 to do the conversion at Auto World
BTW, my '01 3500 2wd Ram never got over 14MPG....4.10 gears.
My '05 2500 4x4 Ram got 23MPG, until ULSD came out; I never got better than 17MPG after that.
My F350 King Ranch 4x4 with 4.10 gears gets 16.2 on the highway, if I'm easy on the go pedal....12.3 around town.