I also have Lines, but I recently picked up the free app from Undercover Tourist. It actually looks a lot nicer and has some extras like restaurant menus and a map view. I do not think it has fastpass return times though, so Lines has the upper hand in that area. Lines also has touring plans.
I've checked both apps occasionally over the last couple of weeks and they seem to be listing about the same wait times, give or take a few minutes.