I've had two Chevys with the D-max / Allison combo. I do not own either of those trucks anymore. Too many problems, mostly stupid problems but dealer visits nonetheless. I had an '01 and an '03 that I recently traded for the '05 CTD. The '01 was also traded for a CTD, my '03 QC. I have had very good luck with the Dodge trucks so far, no problems on any of them.
If you think that anybody elses customer service is going to better... boy have I got news for you. I spent three days fighting with GM customer service just trying to get them to pay for a transmission flush and filter change on an Allison. I did the first one at 25k miles, the fluid was brunt black as coal. I got them to pay for a second flush 2000 miles later as the fluid was dark again. 7k miles later it is dark again and I want something done. They want to give me a piece of paper (ext warranty). What good is that when it fails on the road, flush it out, make it clean, or replace it. It was quite a battle. I traded for the Dodge and told them that nobody spending nearly $50k on a vehicle should have to go through that BS. I was also a loyal customer, five new trucks in ten years time, every one of them required a fight over something. Besides, you would hate how the GM trucks tow heavy loads. The shocks are way too soft, the tires are too small, the mirrors stink, you get the idea, nice cars, marginal trucks.
I second Lightman on the Ford diesel, no way no how will I be a guinea pig for them. They have now turned off the pilot injection making them the loudest diesel on the market, if that matters to you. I also seriously considered the V10 Ford, as I have had excellent luck with my '99 7. 3 truck. The larger 4-door cab is nice, the King Ranch package is sweet but again the Cummins stole my heart. I found the ride of the 3500 CTD to be smoother than the F350 as well, either one is a good bet but if you want the diesel the CTD is the only choice right now. GM is looking at a 20% failure rate on injectors on the D-max, the Allison isn't strong enough for the engine and the general quality of the truck just isn't there. What I do wish, is that Dodge could provide us with some of the options the other offer. Even my loaded Laramie is a stripper next to the LT Chev I traded, same story vs the top Ford. As a truck though, especially one you use for real work, the CTD has earned my vote three times over

Too bad you had problems, dealers can make or break situations like that. It is also possible to get a bad one, no matter who builds them, no matter what they cost.