I’ve also heard people recommend Polaris Office. I remember Documents-to-Go was one of the better options. Things may be better now, but I can’t be bothered to check it out.
It just was not worth the head ache and time I was spending to save the modest cost of the subscriptions. While most of the other Office compatible apps are ok to import or export and office document, none of them stood up to the test of passing documents back and forth multiple times. I only needed Office for compatibility with a few organizations and friends I work with. Eventually I broke down and got an Office 365 subscription.