@Trev Define "good"?
Cross-platform XMPP client for desktop GUI that is not Electron-based, with better security standards than most clients integrated and enabled by default perhaps?
For that particular kind of 'good', I'm quite fond of CoyIM myself.
https://coy.im/
It's not fancy like Adium but it's pretty good on desktop computers.
I haven't seen any decent XMPP clients on mobile though.