I frankly don't know much about the Ford's, so I won't comment on them. Dodge is a cheaply made truck. The use some outsourced components that are very good. The axels, manual transmissions and engines are amoung the best out there. The steering system that Chrysler designed absolutly sucks. It's terrible. Their automatic transmissions are problematic at best. Stick with the manuals for that reason. The Cummins engine is just awsome. That engine is the sole reason, I'd recommend the truck. I'd suggest a 96-98 (not 98.5) manual.
The late model GM's are a very nice truck. The Duramax is a superior engine to the old 6.5. The 6.2 before that sucked rocks. Gm has always used a good automatic behind their engines. The Duramax/Allison is no exception. Their manual is also a good choice. It's my personal feeling that there is no better interior designer on the market. Their bucket seats are very comfortable and the interior is well layed out. The older model also has a nice interior, but the Duramax is such a superior engine, that it's hard to look that far back.