I use both- to me, TGM is a bit more focused on the day-to-day best parks and worst parks to go to (and better at explaining the reasons why). The UG is more generalized. As long as you know the park hours and EMH schedules, you should be okay with UG. My rule of thumb is to hit a park the evening before they have morning EMH hours, or hit them the morning after they have EMH hours. Other than that, you should do fine with either planning tool. I personally think TGM is really informative. You can try it out, and if you decide you don't like/need the information, you can get a refund.
Have fun planning!!