Duramax
It depends on what you're asking they are better about. the Duramax is cheaper to upgrade and has better fuel mileage and stock the Duramax triumphs over the Cummins in torque and horse power. but there is a lot of stuff you can do to them both but the Duramax is all around less expensive. and as to which one lasts longer that can vary, the Duramax has proven to be a very reliable engine but the Cummins also has one heck of a reputation. Cummins= 350hp, 650 ftp of torque Duramax=365hp, 660 ftp of torque
the cummins. Hands down. if you said any dodge older than a 2005, I'd go with the duramax, but the trannies in the 05 and up dodges are much better, and you cant beat a cummins for power and reliability.
Currently it's the Dodge Cummins
The life expectancy of a 6.6L Duramax is 10 years and 350,000 miles. The life expectancy of a 6.7L Cummins is 11 years and 410,000 miles. The life expectancy of a 5.9L Cummins is 15 years and 500,000 miles!
Depends cummins powerstroke or duramax or even a little TDI Jetta are all different
Powerstroke
Everyone is gonna have their own opinion on this. Mine is yes, it is a great engine. In my opinion it is faster than dodge's and ford's diesel engines, and when it comes to towing, it will definitely hold its own. In my opinion, the duramax tows better than the powerstroke and is comparable to the cummins which might come out above duramax when it comes to towing a huge load. This is all my opinion though, I have yet to see an accurate and reliable side by side comparison of the three.
The Cummins motor is not a "Dodge". Dodge does use the "b" series Cummins engine in its pick up trucks. Ford does use the Cummins in its F650 and larger trucks. NO, Ford never has used the Cummins Diesel as far as I know. Up until 2010 the Powerstroke was built by Navistar, formerly International Harvester. In 2010 Ford starting building the Powerstroke themselves but kept the name. Dodge uses the Cummins diesel and GM uses the Duramax which was designed jointly with isuzu.
I would say that the duramax is so quiet because it is overall a better balanced, smoother running engine compared to other diesels.
Probably the best way to get better fuel mileage would be to get a tuner for it.
The best way to get better mpg's is with a tuner/programmer. Most out there guarantee better fuel mileage.