I originally suggested Monal to my friend (who is quite into iOS and really appreciates a well designed application) and she found the same, but then she tried Siskin, and was happy enough to use it to this day.

Just for reference, here are my favourites on each platform.

Each support modern XMPP extensions, interoperate very nicely with each other, and (at least in my opinion) look good!

• Android: Conversations
• iOS: Siskin
• Windows & Linux: Dino
• Mac OS: Beagle IM
• Web: Converse JS

As a note of caution, I used Oracle’s free tier to run a personal Matrix server, and it got deleted without any advance warning after a few months. I migrated to another provider and haven’t had any issues for 2+ years now.