FreeOffice - It's not open source but it's the best offline doc system I've found. It's essentially equal to Microsoft Office and well worth it.

LibreOffice - If open source is really important to you then this is still the go-to office suite. OpenOffice still exists but it's owned by Apache and fairly behind LibreOffice because it wasn't made a priority when Oracle gave it up.

Google Docs/Sheets/Draw - This is essentially the best and most professional solution. It's not open source, you don't have any control over it, it's Google but thousands of companies use it daily without flaws. I use it at work and makes sense to use it if you are going to be collaborating on documents. If you need to share them then this is the goto office suite.

That said, Microsoft Office is very wine-able from what I found. You absolutely shouldn't need it but you can do it.