It doesn't suck, it's just different from what you are used to. Especially the compatibility to Excel-Formulars impresses me.

But of course there are open source alternatives. OnlyOffice is often recommendet if you prefer the Microsoft Office look. I think you could also self host it to make it a real alternative to google docs, but I haven't looked into it.

Avoid Openoffice, it sounds similar to Onlyoffice. It is the predecessor of libreoffice and deprecated.