I have both types of 4WD and personally, I like the AWD for daily driving in various conditions, since I'm in the city now & PT/select 4WD isn't very useful to me.
AWD you get varied output from all 4 tires as-required, all the time and no stopping/shifting is required. The ABS aids in situations where more traction is needed. The center-diff works great so that you can steer the vehicle on pavement, binding/drag nonexistent and nothing breaks or wears out even though truck is permanently in "4WD"
The PT 4WD is more useful for off-road and more-demanding traction situations like muddy roads, grassy slopes, tow/haul, steep snowy inclines where you have equal output from all 4 tires. The downside is you can't use selectable-type 4WD all time like driving interstate in a downpour such as where AWD really shines.
I wanted a Denali for the reason I like driving my LR (AWD) but you get what you get. Here in TX, its hotter than Haydes, doesn't rain for months at a time; when it does the interstate surface becomes slicker than owl shit so people who don't know how to drive, or just have bad tires lose traction driving 60+mph and take out 6 cars. AWD is an added level of comfort, hauling a$$ Up the highway, switching lanes, avoiding other drivers, 100% certain you will maintain traction at all times with a sheet of water on the road surface. I don't drive the 4x4 yukon like this. I thought this was the purpose of auto4, but everybody says not to use it on the pavement so I haven't even been able to use the 4x4 yet