I won't choose between the two and you can't make me!!! I love them both...but for different reasons. We love to keep the UG on the coffee table. That way, we can just pick it up and pass the time, and pick up some tips at the same time. I find it to be pretty right on the mark as far as it's comments go. Do I use the touring plans? No, but at this point I know pretty much what I want to see/do and how the crowds will be. I did carry UG to WDW with me one time, but it doesn't make the trip now.
As for the PassPorter...we get the deluxe binder type each trip. We can keep track of all our daily comings and goings. We really treat it as a trip diary. I love writing it at the end of each day and then going back and rereading it months/years later. The info is good. I have found that I agree with editor/writer Jennifer about the attractions and restuarants. So, if she likes something, I probably will too.
So, for different reasons, I will always get both. And since they both have wonderful websites that I can get updates on, what can be better? Well, the Disboards but I can't carry you all on the plane!