What app you americans use for personal conversations?
Here in South Europe people mostly use Viber.
Edit: I was very unaware about situation in Southern Europe as I've learned from this post...
Most people in Croatia use Viber!
SMS via Google Voice for some very stubborn Americans
Everyone I know in Europe uses Signal or Whatsapp, often both. Sometimes when I suggest to Americans who live in the US that they should use one of those, they counter that I should buy an iPhone and use iMessage.
There are a couple people who are too lazy to get Signal, and they got iPhones, so I set up an iMessage server to forward messages to my GrapheneOS phone.
But the communication there is extremely sparse and surface level. It's basically just a touch point. The real conversations all go through Signal.
Most people I know use SMS/RCS/iMessage or Discord. My family uses Signal, but I don't know anyone else IRL that has even heard of it. I personally don't like Signal because they don't have some basic features, such as if you get a new phone, you need to export/import all of your old messages manually. If your old phone broke or your traded it in already, tough shit. If you log in on your laptop, afaik, there's no way to get your old messages from your phone. I know these were intentional design decisions to make it as secure as possible, but I would be fine with something being slightly less secure to have these QOL features.
There really isn't a single dominant app/service, though apple and imessages comes close. But, since that's apple only, it doesn't truly dominate in the way whatsapp does in some places.
In my local area (a rural mountain zone in the Southeast), the most common single one is telegram. The only thing that gets close is Facebook messenger, but there was a big push maybe three years ago to get people away from it, and it worked.
County wide, it's still Facebook over telegram, but not by much. Then imessage. You can even rely on apple monkeys using one or both of the others since the county school system sends on both of them as well as via SMS for major events.
My kid and most of the high school kids do discord among themselves, but still use the others away from that.
Tbh, though, I have come to prefer not having a single messaging service be dominant. It was (and still can be) a pain in the ass using multiple apps, but at least you're not totally fucked if you refuse to use whatever else the majority have decided to use because it's easier.
SMS/RCS for friends/family in meatspace, Discord for friends in cyberspace.
Snapchat still seems to be a default conduit of communication for my family members and their respective friends. I do not have Snapchat and never will. They are mildly annoyed at my stubbornness.
I have yet to meet a single soul in my local circles who is willing to install any messaging platform over any concern of privacy or security. These are very simply not important factors to any of them. It's upsetting. But, y'know, lead a horse to water, etc.
Discord continues to be a choice platform for my online friends circle. I don't know so much about any of them, but I almost never use it for 1:1 private messaging. It's there for the rare aside conversation. But its primary form of use for me is as a big town square in servers with dozens of people. It's essentially my version of going to the mall after school or to the local pub after work.
SMS. Universal and ubiquitous thanks to free or nearly free inclusion in phone plans. American English has no need for expanded character sets and carriers/Apple/Google have added just enough features on top that the vast majority of people aren't left wanting for more.
Instant payment was literally impossible until this summer, and given it's so new almost no bank has support for it yet. Privacy/encryption don't enter into most people's consciousness.
I just use SMS. I don't need to install anything extra or make some sort of extra account somewhere. Phone plans here have had unlimited texts for like over a decade now so we aren't spending extra money here to send texts either.
So I'm actually an immigrant (Indian) but I came over super young so I guess it counts. WhatsApp with family, normal SMS for everything else. If I could, I would use Signal for everything but it's kind of hard to get your massive Indian family to all switch from something they've used for a decade and a half.
I keep wanting to like Signal but the fact that they refuse to allow multi-device use kills it for me. I can go for days at a time never checking my phone, every app I use also delivers messages to my tablet.
Facebook Messenger. I'm from Australia (but currently living in the USA) and Facebook Messenger is by far the most common messaging app in Australia. MSN Messenger used to be #1, then it was briefly Google Talk after MSN shut down, and now it's been Messenger for a long time.
iMessage/SMS and Messenger are what most of my friends use. Although I know people who use Snapchat at work. I don’t anyone who uses Telegram or Signal.
I do cybersecurity and programming, so, stereotypically, Discord. It's more widespread than Matrix, and it's natively and easily cross-platform unlike iMessage, SMS, Telegram, or Signal.