2 of my kids have iPhones (12 and 15). 1 kid has google nexus (13).
15 year old female has only one friend with android. Use group text - but call android user since doesn't always get her replies.
12 year old female has 2 friends with android. Uses google hangout for group and iMessage for individual messages.
13 year old male has google nexus phone. Uses hangouts with his friends. DH and I will get him iPhone this year, though - since we are iPhone family.
I prefer iPhone so I can use find my friends to see where my kids are.