There is threema, a Swiss messenger that gained some popularity earlier since they had end to end encryption before whatsapp.

Unfortunately the source code is not open (even though they do get annual audits with public reports), and the client costs 3 EUR or something (once).

They also offer Threema Libre on F-Droid for all us folks who degoogled their phone

How about matrix?

Yeah, but Threema has basically no momentum behind it at all at this point.
I'm putting my social capital behind the option that currently stands the most chance of beating out Whatsapp

What does this mean

Don‘t.

Threema has a pretty big momentum in some countries.

A few friends of mine use Threema, because they care about privacy and are more than happy to pay to have it. Signal comes third, behind Telegram, even.

And Switzerlands records in terms of privacy sadly is far worse than most people think - even with the last attack being repelled.

Matrix (preferably on a non-matrix.org instance) currently is the preferable non US and privacy friendly way.

I don’t know - this hype about Matrix reminds me of XMPP which was similarly popular a decade ago. Today, nobody even remembers it anymore.

Then by all means keep that momentum going.
I'm just looking at this from a Dutch perspective, where Signal is seeing by far the most growth.

When you've been around a while, you begin to notice certain trends.

This particular trend being the one where the young, bright, ethical start-up turns into the sort of monster they originally rallied against, ensh*ttifying their product and spouting all the same reasons for it.

Signal is relatively young, bright and ethical. The cynic says "for now".

signal not being on fdroid is a strike against them

You can help making it stronger. That’s what I did in Germany: if people want to contact me, I usually give them my Threema ID first, everything else comes later.

i dont use whatsapp that much anyways

But my goal is not to move to Threema, my goal is to move away from Whatsapp.
Signal fits the bill while expending far less social capital convincing people to use it.

If you leave WhatsApp, your chats will usually follow.

Not all of them.

I have a non-official chat group with some colleagues, and a chat group for the neighbourhood that are not likely moving just because I am refusing to use Whatsapp. It would just result in me missing out on those chat groups.

Currently I just have both installed, and that is also how I try to convince people to install and try out Signal.

Overdramatic blog post,sorry. I can't stand the whole "fremmium" crybabies that then literally recommend the next freemium or "non transparent funding model" service.... And don't understand the fundamental difference between the Protocol and one of its implementations.

Matrix as a protocol is solid and is used far beyond the Matrix messenger. (e.g. the French and German governmental messenger, the German healthcare messenger,various armies,etc.)
With a lot of commits coming from there - but not enough funding,that is definitely an issue.

The current issue with Freemium is solely limited to the matrix.org instance. There are hundreds of federated instances out there that aren't Freemium and won't have the need to go that way as they are funded differently.(e.g. the Lemmy Instance I am currently writing from, feddit - we are financed through other means)
As they are federated it doesn't matter - and honestly, I personally tend to see this as a good thing - it will lead users away from matrix.org towards other instances, making the whole network more reliable and decentralized.

There are two other issues that are relevant, though:
The way the foundation is run is not ideal, definitely - there are and were issues and I am not happy with some management decisions, but at least they are getting somewhat better recently (government board). The whole protocol does not evolve as fast as it should be and this is an issue,especially as a it also affects bug fixing.
As an executive for a (much smaller) company myself I see management issues and infighting due to lack of leadership within the foundation and I am not happy with that.
The second issue is Element as a company that does things companies do - focus on making money. This in theory would be a good thing if Element would send enough money AND effort upstream to seriously bring the whole project forward. For a long time this seemed to be the case,but licensing issues and the "stale" development off Element X(Matrix 2.0) has me questioning that as well - but recent changes show us hope in that regard.
We also need to carefully reconsider if element is keeping too much"closed" source code for monetized features and what influence VC really has.
In conclusion: We need better leadership for Matrix,more transparency and more funding.

The good news is: It doesn't mattter too much - if the current foundation fucks up and goes belly up it is not the end of Matrix - the protocol is decentralized enough and the licencing of the core components permissive enough for another (better?) foundation to start over. There are dozends of clients available and we have alternative servers available by now.

The funding part nevertheless is my major pet peeve here.
All around Europe governments try to get rid of US tech - and use Matrix protocol based products. But they hardly if ever fund that. If Germany, France, Poland and Luxembourg (the big users) would give 5€ per year for each client they implement all issues with funding would be gone, Matrix 2.0 would be available in a few months, VC could be pushed out of elements AND they could mandate more transparency.

The issue with funding is relevant for all NGOs and especially in tech. Running servers costs a fuckton of money.

Signal has a respectable amount of backers but is a centralized protocol and when Trump does something shady moneywise their infrastructure,money and possibly even people will be gone within 24 hours.

Threema has a more sustainable business model but Switzerland is,well, difficult, in terms of privacy and intelligence services overreach, especially towards traffic pointing to foreign servers or hosts.

Revolt is a centralized service with no federation,limited selfhosting capabilities,with unclear funding(we are waiting for a financial transparency report for ages now).

Polyproto is still not quite there feature wise and funding, etc. is unclear.

Delta Chat is indeed an option but has massive technical limitations.

That leaves XMPP as the sole big competition if you want non-centralised, non-US based, privacy friendly, messaging.

Pepperidge farm remembers, and so do I. Lots of people I know use XMPP (Cheogram, Dino, etc).