Osfoora is a lot like the official Twitter for iPhone app was before the recent changes in version 4.0. That is to say, anyone who liked the original Tweetie will be immediately familiar with most of Osfoora. But Osfoora doesn't just stick to conventions, it jams a lot more features in as well. There's everything from a "home screen" with big icons for major functions to unread badges on the major sections.
For years, Plurk offered the service that is nearly identical to the ones provided by Twitter, and it increased the number of character you can use in a post to 360 just a few years ago. Nearly 70% of all the traffic on the platform comes from Taiwan, so if you are targeting markets in Western Europe or the United States, Plurk may not be the best social network for you.
Trolls, haters, racists... are on every social network. Gab also have racists. Mastodon blocks nazis and allows you to create your own social network. The best alternatives to social media are web hosting sites, blogs, file uploading and file mirroring websites and link bookmarking websites. They don't store too much personal data and there is no trolls, spammers and haters.
A simple chat (slack style) it's enough. Just having the possibility to send messages either single user or team (#channel). But please don't forgive to give an useful appeal to mobile app (worst error of competitors is, have a good app but totally no mobile friendly!) i would expect to have a similar whatsapp or slack app for messaging within the slack mobile app!