I wonder what you need in Word, for the tasks you described, that Nisus and Mellel can't do. I know several people who have written dissertations (myself included) with one of the two, and who regularly submit academic works to publishers with those wordprocessors.
You are not the only one who absolutely wants Word, or don't feel at home when writing. It's really a mistery why you don't simply use it.
Mellel and Nisus Writer Pro are both good word processors and they are able to do everything I need, or nearly everything.
Still, Word 2013 for Windows is more convenient. Word has a better interface and is more intuitive. Word has grammar checker in Portuguese, and both Mellel and Nisus lack that, and it is useful for me. Word has a thesaurus in Portuguese, which is very handy to use.
Word can split a page in two so I can work on both parts of a document at the same time. Word has a draft view that allows me to work with footnotes, and neither Mellel nor Nisus have that.
I can of course send files to publishers with Mellel and Nisus. But I have to convert them first, and make sure that the files are still readable under Word. If there are issues, I must correct them before sending. Plus, when I receive a file back, I must open it with Word first. If I receive a manuscript from a publisher, it's OK to use Mellel or Nisus.
However, if I receive a document from a client, I must keep the formatting in order, and therefore I must use Word.
Want it or not, Word 2013 is still the best and most fully-featured word processor available. Nisus Writer Pro and Mellel save the Mac, as Apple does not care about it. But still, Microsoft has a multi-million (or billion) dollar budget to develop Word and polish it to perfection. Nisus and Redlers are both small companies and have limited resources to develop their software. While Nisus Writer Pro and Mellel are good, or even great, you cannot simply compare them to the crushing power of Word.