From our side we recommend the following clients:

• Android: Conversations (€ 2,39 from Google Play or free of charge from F-Droid)
• iOS: ChatSecure (from App Store)
• Linux (desktop): Gajim with plugins "HttpUpload" and "Url image preview"
• Linux (console): mcabber or Profanity
• macOS: Adium
• Web (Browser): Converse.js
• Windows: Gajim with plugins "HttpUpload" and "Url image preview"

There is a more detailed overview here.