Well, I guess this is just like Yamaha/Merc/name-your-favorite-brand-here discussions. Everyone has had their own issues and horror stories with every brand out there. No one is immune.
That said, we have a '99 F-250 with a V-10, which hauls 4,000 lbs. up and over mountain passes just fine. 185k miles later and never had a major issue with it. If you're pulling 3,600k, then a 250 will suit you just fine. A 150 or 1500 is a little under powered, especially in the tranny and rear-end dept. The 250 and 2500 have bigger brakes and beefier suspensions too. You'll need that for panic stops while towing.
We also have an '09 F-450 dually with a 6.2 diesel. I hauls 10,000 pounds up and over the mountain passes easier than the 250 pulling 4k! Never would have expected that. I guess 650 lbs of torque will do that.
Only issue we had was the hose clamps to the turbo weren't torqued right at the factory, and the hoses blew off the first time we towed. 10k later and no issues since.
Never had any problems with the dealers either. In fact, when the hoses blew off, the dealer sent a mechanic out to fix it right there on the roadside! Now that's service!
I have heard of issues with Ford '06 - '08 diesels. I understand Ford completely redesigned their diesel engines for '09, and they're much better now (btw, talk to a mechanic before buying any truck, not the salesman. He'll give you the scoop.). This is why I recommend the '09, and not an earlier model - at least if you're going with a diesel. But if you're not considering a diesel, then the gas engines are fine any year.
I don't have any experience with other trucks, so I can't speak to that. However I used to have a '74 Camaro, and ran that well past 300k miles before it needed a rebuild. Regular oil changes and services make all the difference, regardless of brand. But that's true of outboard engines too.
