For me the answer is absolutely nothing.
I do a lot of work with Excel and writing code in VBA, but when the recent details of Microsoft's Security Violations came to light we had to investigate the changeover to Linux ( My secondary machine is Linux Mint and has been for nearly a year now).
Libreoffice actually was very good, and although it means an entire rewrite of the codebase (fortunately not as big as it sounds) which does the data mining research as Libreoffice is very different in the way code needs to be written to interface from Excel VBA, it was actually not a great issue with over 90% now ported (although the last 10% will take time due to lack of documentation at this stage).
The biggest Issue I have is that NTFS on Linux is a bit of a hack and I dont consider reliable, meaning I have to transfer something like 40+TB of research raw data to drives formatted under EXT4, and verify the data (Tip - Try DC++ to generate the TTH for the files so you can compare), before the previous source drive is reformatted for the next transfer of a drive. As im working with sensitive data I have no choice but to ditch Windows for good after air-gapping the network for now.
When it became apparent what was happening with the Microsoft/NSA spying, it sent shudders down my spine, I am trained in PCI Compliance and data mining
Goodbye Microsoft, you may have had me as a customer for over 30 years being an IT professional, but no more. The only issue I have now is finding a good antivirus (dont laugh I have used Trend for sometime, and they just dont have one as Linux is a lot more damn secure than Windows).
Where Do I want to go today? Definately not with MS.