I also buy the UG regularly, and am a TGM subscriber (multiple times)
UG is like the farmers almanac. IT has tons of information. I have planned great trips using the UG alone.
TGM is a lot of background info, descriptions, recommendations etc but it is also like the weather channel with regular updates on what is happening now. When things change (like EMH schedules, and ticketing) no book can beat TGM.
Passporter is a great organizer. I like the format and the maps, but that is about it. I plan on buying one of the updateable versions and making my own pages from TGM and UG info.
I recently went to Barnes and Noble and looked through all there guidebooks.
Some of them are hilarious... one suggested for MGM to get there for park opening proceed directly to ToT get a fastpass then... this is the good part... leave the area and go ride GMR then experience the animation courtyard. WHen time for your fastpass return to Tot and ride it then go to RnR and wait in the standby line if it is less than an hour... WHO WOULD DO THIS!?! Wait for an attraction for an hour when everyone knows you can 1)fastpass it or 2) ride at a different time where you can basically walk on...
Oh, do NOT use the touring plans from DK Eyewitness guide. I like there format and info, but the plans aren't worth it.
You should be able to get everything you need from UG, TGM, Passporter, or the DISboards or some combination.