In 2012 I used a crowd calendar for planning. Everything was still crowded.
In 2014 I tried a different one. Everything was still crowded.
In 2015 I worked there. Every day, everything was crowded.
The thing to keep in mind is that each provider is using anecdotal, crowd-sourced evidence to make their predictions (because Disney does not release actual metrics or results to anyone.) When you look at all of them side by side, each one gives you information that is sometimes very different. That variance is a good indicator that everyone is really just guessing, and no matter which one you pick, the predictions may match your actual experience, or they may not.
As time goes on, the difference between "slow" and "busy" days is much less noticeable.
If you're going to use any of them, make sure you're using a free one, and don't expect it to be exact.
Personally, I plan my park days around the reservations I want (FP+ and ADR) and am actually able to get. Anything else is really just guessing.