There really aren't that many that check all the boxes.
WhatsApp is the most popular globally but your phone number is mandatory for registration and it's owned by Meta.
WeChat's user base is confined to China, and its web app isn't available outside of China, afaik.
Facebook Messenger is an extension of Facebook, and again, it's owned by Meta.
Snapchat doesn't have a web app and its best feature is also its worst feature (disappearing message), depending on your use case.
Skype is tied to your Microsoft account. Like Facebook Messenger, it's not a fully independent service.
Telegram is pretty much the only one out there:
- that has a large global user base
- where your phone number is optional for registration
- that has a relatively good track record in terms of privacy protection
- that's not an extension of another service
- where disappearing messages is optional
- where message translation is built-in
- where your Telegram account isn't tied to any other account and you can come and go at ease
- has native apps for iOS, iPadOS, macOS, and web
This is not to mention its UI is the most intuitive and clean (personal opinion).
I have all of them (plus Signal and Instagram messaging), and I really don't care which I use, just whatever the other person uses, or whatever suits the use case the best.
- They all work for exchanging messages.
- I don't care about giving out my number. There's this thing called blocking someone if really necessary, but simply not replying works well. What's the worst that can happen if you give someone your number? They might call or message you? Oh wow, how terrifying.
- I don't care about "privacy" or which corporation has bots trawling my messages for keywords, as I use ad blockers extensively, so none of their ads ever reach me anyway. It helps that I use my MBP rather than my phone for almost everything.
- If I genuinely have a secret message to send, I use PGP and exchange public keys with the person I need to swap encrypted messages with. It's open source, which is the only possible way to know if claimed privacy is real, and you encrypt the message yourself, and then can send the encrypted package via any means you like. Only the recipient has the power to decrypt it, since you used their public key to encrypt it, and only someone who has their private key can decrypt it. Yeah, it takes some effort to do that, but you then know for sure that it really really really is private. And you've gotta ask yourself, how often do you genuinely send a message that is truly private, and if you dig deep enough, the answer is almost never.
- Some have this feature, some have that feature, so if you have them all, then you have the freedom to use whichever one serves your purpose at the time.
Note 1. the only one I don't ever use is iMessage, as our family discovered that it can lose messages. I'm serious! We had messages go missing. So we all turned iMessage off on our phones permanently.
Note 2. Surprisingly, the one I prefer to use is FB Messenger. It works wonderfully on both Mac and iPhone. It's easy to add attachments. Can do groups. Can see if a message has been sent, received, viewed. Can deal with attachments wonderfully. Can send group messages easily, simply using peoples' fb profiles. The only notifications it sends are for new message arrivals. And so on. The only downfall is they need to have an fb account, and you need to be fb friends or the message can get lost in the mystical hidden "message requests" folder. And yeah, I really don't give a toss about Meta trawling my stuff for keywords, as I ad block everything, and don't waste my time on my fb feed.