All alternative products I have used so far have worse UI.
Slack is always laggy and does not even handle markdown well. Recently moved around buttons for huddles and people keep searching for where that button is. Also annoying, that pictures can only be attached to the end of a message, forcing me to reference with something like [1][2] and so on.
MS Teams: haha just joking. Of course it cannot even be considered close to an alternative!
Discord: Was good some time ago, becomes ever more bloated and heavy now.
Element: When I tried it some time ago, it was very unclear how threads actually work and they did not seem to have any visual separation from other messages, that simply came later in a channel. Basically messages know they belong to a thread, but visually you almost cannot see it. Not sure, if that is still the case.
Zulip is snappy and works well with markdown. I find it looks much cleaner than Slack and others.
Not only does it look OK to me, but the UX is second to none. I don't like the modern design trends with white space everywhere, I want to communicate and that means dense information.
I think the design issue is more of an HN meme these days, than an actual problem.
Most of the time I also enjoy pretty dense UIs, as long as I don’t have a significant risk of misclicking on things that are too small.
That said, I rather liked what Thunderbird and JetBrains did - let the user choose not only the fonts and stuff like that, but also the UI density that they want.
That is in fact one of the new features in this 9.0 release! There's a new less-dense default, and the previous dense layout remains an option (which for myself I immediately turned on).
We're also planning to give a wider array of options in an upcoming release, including independently setting the line-height and the font size. It's a lot of work to get even two options to both have a reasonable layout throughout the UI, though (among other things, it involved changing a lot of hardcoded values in px to be in relative units), which is why only the two-way switch made it into this week's release.
Slack is always laggy and does not even handle markdown well. Recently moved around buttons for huddles and people keep searching for where that button is. Also annoying, that pictures can only be attached to the end of a message, forcing me to reference with something like [1][2] and so on.
MS Teams: haha just joking. Of course it cannot even be considered close to an alternative!
Discord: Was good some time ago, becomes ever more bloated and heavy now.
Element: When I tried it some time ago, it was very unclear how threads actually work and they did not seem to have any visual separation from other messages, that simply came later in a channel. Basically messages know they belong to a thread, but visually you almost cannot see it. Not sure, if that is still the case.
Zulip is snappy and works well with markdown. I find it looks much cleaner than Slack and others.