The #1, most immediate feature I always want out of a chat application is "please scroll back up to the last time I made a comment, so I can read the replies". Bafflingly, no chat app in the world has a dedicated button for this, and each one makes you memorize a semi-standardized syntax that might begin with author:, might begin with from:, might support "me", might require you to type a 12-digit handle, and might not exist.