MSFT and Facebook
The kings of slurp, way worse than Apple or Google, who are both transparent with what's collected and honest about rentention. I did a paper on some tests I did about data deletion and it's after affects, it was crystal clear that Google and Apple did the right thing and truly forgot me, but Facebook and Microsoft didn't. Even 3 years later, Facebook data is still retained about me, my IP address, and people I may know.. Microsoft are still using things it knew about me for advertising.