There's a dizzying array of indexing packages available on CTAN.
For my current project, I'm using LuaLaTeX, but most of the time I just use straight LaTeX (and on occasion XeTeX).
My needs for this project are pretty pedestrian: the book I'm typesetting is in English, and I don't need any sort of custom collation. However, it's not really clear to me what the best choice is.
I noticed that some of the packages make reference to the
memoir class, which I am currently using.