Read receipts: when an iMessage is sent you will see a text saying that was delivered and read. You don't have to wonder if your partner did not read a very important message about picking up a potatoes bag at the grocery store.
Live typing: you will see that other person is typing you back with a 3 dots symbol.
Device syncing: can read and send iMessages from your Apple computer, MacBook or iPad.
Stickers and effects: like exploding confetti when you send "Congratulations" for example.
Not being a green bubble in your friends iPhone😁
You can send voice texts and if you are a gamer, you can host rounds of multiplayer games without leaving the app. You can play board games, 8 ball pool or even have a basketball shooting competition.
These can't be used if your recipient has an Android.
Google is trying a service similar but it will not be compatible with iMessage since it is hosted just in Apple servers.
You're probably the kind of person who will change your make of car just because the turn signals are yellow instead of white, or you bought a 2020 model and wanted the options of a 2022 model. Concerning SD cards at Samsung, it's like when Apple took the floppy disks out of its computers, everyone whined and when we decided to remove them from the PCs, we whined again. It's like in politics, once you vote conservative and the following elections you vote liberal because you think that the conservatives have lied to you then you realize that the liberals are even more liars and that in the end you should have voted conservative because they are all the same after all.
Have a nice day!