The only other Word processor that I use in addition to MS Word and MS Office (which are 2 separate apps) for Word is OfficeSuite Pro, since it can run RTF files (Word and Office can't on iPad, contrary to Android).
I got it back when MS Word did not exist for iPad yet, and don't know if things have change or if part of it has gone with the terrible subscription model in the meantime, but it's a good alternative.
Pages runs RTF files too, but screws them up most of the time, it's really not very good with files made with desktop Word.
PS As I teacher I have full Office365 for free