QuickOffice is pretty good. Polaris Office is another good choice.

Where they run into limitations first is support for all of the radically incompatible "cloud drive" services out there. Of course MS Office is even more handicapped in that regard, though it makes a bigger target for 3rd party add-ins.

It is a pity that the perfectly good standards we once had (WebDAV & CalDAV) got relegated to niche status due to the flaws in PHP.

Wish More Hosts Offered WebDAV? Blame PHP!

There are lots of reasons why so many pronounce "PHP" as "poohp."