- Have more options for blocking, including "block this person and everyone who follows them or followed them within last N days"
- Fix trending topic spam. Seriously, how is this so bad? Free advice: for every trending topic a tweet mentions over 1 in a single tweet, the probability that it's spam asymptotically approaches 1.
- Allow an unambiguous, never "played with", chronological timeline. Have a separate view that's your ML playground. The "In case you missed it" and "tweets you might like" features are good but I don't want them randomly appearing in my timeline.
- Allow alternate clients, even if you have to charge a fee.
- Similarly, create a separate free developer-focused API but clearly identify all tweets posted via that as "bot" and allow people to never see tweets posted by a bot, or tweets posted by a bot @ them. Tweets posted from the "alternative client" paid API would not be subject to this marking.
- Identify "sleeper cell" bots -- accounts inactive for a long time that suddenly become active, usually around a single topic, concurrent with many similar bots, and aggressively ban them.
- Do more and better things with Lists. Don't just show me 3 people to follow (usually clearly just based on the last person I looked at). Show me algorithmically curated suggested lists, popular lists, allow me to sort those by # of members, easily find lists that user X belongs to, etc., mark lists as low quality/harassment vehicles. Surface good content shared by my interest lists somewhere other than the timeline.
- My personal #1: give me the likestream of the people I follow. This is easily more interesting than their actual tweets, at least to me. Something like a quarter of my usage these days is visiting individual accounts "Likes" pages. At least use this data in the aforementioned algorithmic curation of Lists/suggested follows.