The only thing that matters to me is total and absolute privacy, I should be able to chat with people I care about and not have any third-party involved. No advertising companies, no anonymous collection, no state surveillance, nothing. I don't want anyone scraping my business for any purpose. I'll pay to have it that way if I must (thought I don't see why I should have too).
I don't care about stickers, emoticons, videos or anything else.
I know apps exist that do this now, but this needs to be the default behavior and there should be an open standard for achieving this. It's 2017, we should've had this in 1998.
If I can't have something like this soon, then I'll make it myself.