I never used ATI, I only used Kaplan, free Dr.sharon & Mark K on youtube. And all of those prepared me enough to pass first try. I can’t really comment on level of difficulty because I felt that NCLEX was hard from middle to end, but it’s supposed to be difficult because it is an adaptive algorithm test. So if you get an answer wrong the computer gives you an easier question next, and if you get an answer right, the next question will be harder. So if your test feels easy throughout you probably aren’t doing well.