iMessage? Natively on your phone/macOS and peer to peer encrypted. Never really saw a need for yet another messaging service. I think I'd trust Apple to do the right thing over any of these.
Great unless you or someone you want to communicate with doesn't use an apple device. Which covers the majority of the population.
I've also had terrible reliability issue with imessage in the past, messages not delivering, not showing up, errors sending, showing up on one device but not another, etc. Was a mess that caused a lot of confusion.
Guess it depends on your circles. For my group, everyone has an iPhone or a Mac. For the outliers, everyone has cell phones, and iMessage supports SMS.
