The one I use is call DLR Lines and it's ok the only thing that is not right is like when say Pixie Hollow or the meet and greet for Brave are close they still show it as open. Like Brave closes at 3pm but like right now it says it has a 22 min wait. posted 25 mins ago. So it's not that accurate with some of the meet and greets.
I've found that Mobile Magic, the official one out out by Disney, is the most accurate, but it only works in the park you're visiting and lacks a few things such as restaurant/meet and greet wait times.
I used it yesterday when it was very busy. Mousewait was very inaccurate throughout the day and showed that there were two showings of WoC when there were in fact 3. I usually use Mousewait, but on a busy day when wait times fluctuated so much, it just couldn't keep up.