Having tried both, I definitely agree.

* MeshCore has a lot more reach than Meshtastic. Often 100+ kilometers compared to just a few kilometers. Even if MT is more popular in your area, there's a good chance that MC will give you far more actual range.

* The online node maps for both are unreliable. I don't recommend relying on them for anything.

* Meshtastic uses a basic flood algorithm, up to 3 hops by default and with a hard limit of 7. Every device works as a repeater.

* MeshCore distinguishes between Companions and Repeaters. It uses flood routing by default, and attempts to establish smarter direct routes where possible. Companions are end-user devices for sending and receiving messages. Repeaters are ideally mounted high up in a static location, and they forward packets they receive. Companions normally don't act as repeaters, but can do so if needed in off-grid situations using the "off-grid repeat" setting.

* Some are concerned about whether MeshCore is open-source. The firmware contains everything important, and is fully open-source. The official companion client app is closed-source freemium. But it's simply a GUI that talks to an API over Bluetooth, TCP, or Serial. The official CLI client is open-source, and you can use any client app you want, including the popular MeshCore-open app.

I don't think this is quite accurate advice. Go where the activity is. Around me, in a city of ~1.5M, the Meshtastic community is quite active. They've worked with local ham radio clubs. They have members setting up a larger mesh that stretches the state from north to south. Meshcore isn't as active, although people are experimenting with it just like Meshtastic. But because Meshtastic has more local users, that's what I would recommend to people here. Meanwhile, places like the PNW and Boston have adopted Meshcore. So I might recommend new users there to try Meshcore. It's okay to have both.

This us vs them/there must be a winner attitude that I see in both communities is really toxic and unnecessary. Look at ham radio: some people use CW, some people use SSB, some people use SSTV, some people use FT8 (but not everyone! There are still hams using other digital modes), many operators dabble in a mix of the above. There are a variety of options and nobody is pressuring other operators to use a particular mode or band.

Maybe it depends? In my city, the online map shows only 2 Meshcore nodes, while Meshtastic 36 nodes.

And I've never spent time learning about it, but I'm under the impression Meshtastic is all about open-source and closer to ham radio philosophy, while Meshcore is backed by some for-profit organization?

The biggest problem with Meshtastic is that discussions about it inevitably get spammed by Meshcore evangelicals.

I assume there's no firmware that can speak both, or create a bridge?

Is there something preventing people from just setting up both?

This is bad advice. The choice depends on which is more popular in your area. For me in Phoenix that’s meshtastic.