I was actually not a big fan of Detroit, I had a few and they didn't seem to be as reliable as the others. I would have to say for pulling power and smoothness the Cummins ISX was spectacular. The Cat C-15 was a good engine no doubt, but the ISX was superior in its technology. Smooth, Reliable, and got decent economy also. I had 2 trucks with an ISX. First was a 2000 Volvo 660, and I drove it for over a year with only one breakdown, and that was an idler that seized up because the bearings were bad. The other one was a 2005 Volvo 670, and I drove it for about 8 months with no troubles at all.
The detroits always seemed to be a bit underpowered and used more oil than the others. They were more economical though, so its a trade off. I really didn't have any major complaints about any of them, they all did the job.
Now as far as Truck manufactures go. If I were to buy a truck of my own, it would be a Volvo hands down. The construction was solid, I liked the computerized features in the newer 670's, they had way more room in them than any other models, they were superior in manuevering around the docks and truckstops, and they rode very nice. Espescially the 2005 that had Air ride front axles.
If you wanna look like a Pimp Daddy then the W900 Kenworth and Peterbilt 379HD are the way to go. Both look cool, but have their drawbacks. Mainly in manueverability, and they are very cramped inside.