I've made the switch to Signal, my girlfriend uses it on her iPhone to replace iMessage since I made the switch to Android last month. She can also use it on her Windows laptop unlike iMessage. My family members who are tech-y enough use Signal with me, and when they're not, I can still send standard SMS through the app. Signal even implements responses similar to iMessage 'likes' and 'hearts'. I don't think I could praise Signal enough for the great implementation they've built. Their crypto-enterprise this past year did make me feel a bit slighted, but as I don't use that feature, I can't comment on it.