For me:
* Let me opt out of all recommendations. I only want to see tweets of people I follow or tags I follow. Nothing else. I'll find more people to follow via the people I follow. Do not post random popular news, people, related stuff in my feed, period.
* Let me choose the types of tweets I see. Personally I want to see zero of (@person liked, @person replied to, ...)
* Remove the 280 character limit (but possibly only show the first N characters in the feed). I don't personally believe the 280 character limit is important to twitter's success. Twitter's difference from most other places is that people are talking from their account, in public. It's one giant flat public forum. It is not FB (friends and family) and it is not Reddit (moderated sub forums). That alone is it's strength. All the 280 character thing does is amplify hyperbole as there is on room for nuance.
I'm sure Musk has his own ideas (no censorship?) but as for me, I won't personally use twitter without the changes above. I have an account, I check about once a month or less. I see lots of the stuff above and quit. It's like having a pushy salesperson following you around and constantly recommending stuff. Rather than more sales I'd just leave for another store.