Recently, I’ve been using Kakaotalk over Kik Messenger and Viber. The thing here is Kakaotalk has more customization options compared to the said other services.
The best feature for me as for the moment are the smilies. They are simply unique and lovable, and they’re animated. They’re like the real “emotions” you really want to express. I have yet to discover its features as I’ve only been using it for a few hours but so far I’m enjoying it. The only downside is that the features for Blackberry phones are very limited right now but they did say something about an upgrade. It is available for iOS, Android, Windows Mobile and Blackberry users. Check kakaotalk.com