Both are accurate if you use them correctly.
EASYWDW is much more like the Tour Guide Mike park recommendations. And that was the only thing I found worthwhile at TGM. Of course, not worth what you had to pay. IMO, that is why Easy WDW is popular.
Touring Plans (The Unofficial Guide) is based on a whole different theory. If you read through how it is calculated and understand it, you'll find that it is pretty spot on.
BUT, that is the key. Each calendar is arming you with different information. Used together, you can't go wrong. The lazy way of doing it (the way I do it), is use Easy WDW to pick your days. Just use Touring Plans/UG to decide between ties and how to tour your park for the day, or if a park you're forced into for the day just doesn't fit.