I've never had a problem with mixed Android/iOS group messages and media with iMessage. I've made no special effort to get it to work. It's seamless. Am I doing something wrong? Or right, rather?
Now, back when I used Android I remember Hangouts ruining everything it touched and I had to switch back to the deprecated Messages app (which was completely fine and did not need replacing) to fix it. Maybe the problem with the Android users on these group texts isn't on the iMessage side....
If you associate your phone number with an iMessage account, and then deactivate iMessage, Apple will just silently stop delivering group iMessages to you. You won't notice and your friends won't notice, they'll just stop coming.
Now, back when I used Android I remember Hangouts ruining everything it touched and I had to switch back to the deprecated Messages app (which was completely fine and did not need replacing) to fix it. Maybe the problem with the Android users on these group texts isn't on the iMessage side....