I tend to prefer OnlyOffice, if only because it's open-source (unlike SoftMaker), and has better compatibility with MS Office documents.

You can't shut down a decentralized alternative, which already exists with the Fediverse.

A facebook ActivityPub alternative already exists with Friendica.

https://friendi.ca/

Don't forget FreezeCrowd!

https://www.freezecrowd.com/

Context: https://www.youtube.com/watch?v=dQx_pJyyyxc