Down here, they sell more diesels than gas trucks. When I was shopping for my 250, I'd guess it was around 2/3 diesel and 1/3 gas inventory. I have a '15 250 diesel and my neighbor has a '15 350 diesel. Other than his tailgate getting stolen, not a single issue with either one. I did get the extended warranty for any engine repairs if I keep it that long. The '15's may not be selling quite as fast because there's a redesign coming for '16 I think. With rebates and discounts, I got almost $11k off sticker.
I was looking for a gas truck too, but ended up with a diesel. Many friends told me to get the diesel since it will tow way better and the resale value is much higher, and more desirable when traded in or sold. I ended up with a '15 250 Lariat diesel 4x4 crew cab and really like the truck.