To be fair Kontact (KMail) had its bad days. The whole Akonadi stuff underneath got a really bad reputation because of that. And that was for a reason, for sure

To be fair Kontact (KMail) had its bad days. The whole Akonadi stuff underneath got a really bad reputation because of that. And that was for a reason, for sure! But those issues are solved today (and since a long time by now). I don't know whether Kontact could be considered substantially better than Evolution. But it works fine and has a lot of features not found elsewhere. It's also quite focused on power-users I would say. For example you have configurable one-keystroke commands for all important functionality (and being a KDE application you can configure shortcuts for actually every action if you like to). It handles big inboxes in different accounts (being capable of showing an unified inbox if desired) and independently of that multiple identities. The calendar and mail components handle Exchange idiosyncrasies. The GPG stuff just works. For people looking for a true Outlook alternative on Linux it's at least one of the things worth trying. That's why I've mentioned it.