I still use all of these sometimes, but mostly I use these free, open-source alternatives:
Possibly less susceptible to viruses than Windows, and I find it less annoying. It comes bundled with lots of useful programs, including ones that can work with .docx and .xlsx files, though not all Office features are included and there can be some changes to formatting, placement of images, etc.
Google still has lots of my personal information to sell, because my university makes us use Gmail, GoogleDrive, etc. But Google’s motto is “Don’t be Evil” so I guess I shouldn’t worry.
Encrypted synchronization of files among my computers, without storing it on anyone else’s server. It can only synchronize computers that are on at the same time, so I set up an always-on Raspberry Pi as a private server. This still doesn’t give me some of Dropbox’s backup and sharing options.
The third time a reference-manager company I was using disappeared, I wrote my own Python program to manage references. It’s not as fancy as commercial options, but I’ll always have it.
I’ve never used Twitter or Facebook. Am I missing something important?