While at it, should we put Segment, Mixpanel, Optimizely, etc. on the list? I’m not saying they’re good or bad in terms of data tracking, I’m just saying they should be in the same bucket. Tech companies harvest data to improve their businesses...

Well, while we (Countly) are direct competitor to Mixpanel, we cannot talk about this as there is no evidence and all of them are clear about what they do with your data. Speaking of product analytics, the best way is to keep your own data on your premises (shameless plug here).