Nice Truck. i've owned my 14 GMC 5.3 SLE Z71 double cab for just over a year now, and really like it. Traded in an 03 F250 Crew for it. Went from 12-13 mpg, to 18 mpg, and 23 mpg average on a trip to TN.
Personal tastes, I liked the looks of the 03 F250 crew, it was big, bad and it rode like a truck. Unfortunately like 85% of the superdutys of that age, the rear wheels wells started to rust, which prompted looking for another truck. The 14 GMC, has more of a luxury ride which is nice, and I love the options that it came with. The down side, storage sucks for truck stuff like tow straps, tie down, etc. The F250 rear seat folded forward, and you could store stuff. The GMC seat doesn't fold forward, the bottom lifts up, and basically you can put stuff on the floor which can slide all over. I ended up purchasing the under seat storage once it was available, but its still not the same.
In the F250, the crew portion was not used very often because the truck was taller and didn't ride as nice, so I choose to try the extended or double cab this time. Of course it would figure with this truck, it easier to get in, and rides better, I could have used the crew cab more then ever before. Good thing this one was just a lease, will definitely be returning to the crew cab next time.
Mike