Explain Everything is the editing platform that students at my school have been using. It is not an app that I purchased, but was highly recommended by teachers. It costs 2.99.
I use Notes the most of the editing apps that I have on my ipad. I try not to do much typing on the ipad. I have extensive files on my PC and can access them both at school and at home, so it is not vital that I be able to edit.
The other apps that I have tried are:
I have used them all but find that my go-to app is still Notes. I guess that I don't need the extra functionality in daily use. I do store documents that I'd like to access on the iPad in Skydrive. That way, I can view what I need from any device that I happen to be using. Skydrive doesn't allow editing on the iPad, but that hasn't been much of an issue for me.