Long range Arduino communication

Hi everyone, I have those 9 arduinos separated by the distance showed on pic, and all 9 arduinos must send information to the Arduino Master, Any Idea about the best way to do the comunication between those 9 arduinos and the master?
Initially are 9 arduinos, but possible to be more in the future.

WiFi, LoRa, 433mhz module creating a net. Whats the best way do to that? Planning to star a research on how to do that.

Mesh network.

You can use Meshtastic or RadioHead RMesh with LoRa radios for long range (kilometers, line of sight) or BLE/ Bluetooth UART-serial modules for short range (10 meters). All support up to about 250 individual node addresses.

ESP-NOW is worth a look, too.

How well do these work? I ask because I tried doing mesh and point-to-multipoint (when mesh wasn't working) with Xbee radios about 7 years or so ago.
I found Xbees to be a nightmare to work with, but I was still very green to the hobby and could never get them to work right, every time I powered up.

Make sure you factor in the data payload sizes, rates, simultaneous or overlapping transmissions…. polling or asynchronous ?

Extremely well, under good conditions. However, "good conditions" will depend on where you try the experiment.

Meshtastic is very simple and popular, but works only on very few selected platforms.

No mention of reliability. That means error detection and retransmission to possibly correct the error. No mention of system monitoring so a failing unit can be identified and replaced.

Add ESPNow to your list.
Leo..