The best I've found is IM+. It's not ideal, but frankly there's not really much choice. Unfortunately Google has switched to a proprietary chat system with Hangouts so IM+ (and other 3rd party Google Hangouts apps) are not able to utilize all the new features. That is, you cannot group chat, send pictures, or do video calls.
For group chats, you're just outta luck. For sharing pics, I have taken to auto-uploading to OneDrive, then going to the app, selecting the photo, and copying the share URL. You can then paste it into an IM+ conversation. Not ideal...but again, no choice until Google makes a Hangouts app (don't hold your breath). As for video calls...you'll have to get your friends to switch to something else like Skype.