My last 3 truck have been GM products, the last two were diesels. I've had some issues with all of them but nothing major so I've been happy with all of them. Current truck (2013) has 105k, the last one (2004) had 160k. My next truck probably will be the new generation GMC 3500 and definitely the diesel again, the Chevys are too ugly although they are slowly growing on me - yikes! One reason I would go with the GM is because I believe the Duramax is the only one that does not use the CP4 fuel pump like the Ford and Ram do. Plus as controversial as the looks of the GM offerings are they have a lot of cool tech on them and very capable.
Dan