If you have some time, you might want to hold off and watch for the reports on this new adapter:
The Silabs group seems to be the leading folks right now in terms of current products (Zigbee 3.0), processor horsepower and configurations option for the coordinator.
I have been running one of the Sonoff Zigbee Tasmota’ed for a bit with good success, and have used the CC2530 in past (not recommended, while very stable, old tech and very underpowered for larger networks). As @makai stated some of the in the know folks around ZHA say that the way the Sonoff Zigbee coordinator device connects to the ZHA software is not a good model and may cause issues (I suspect with larger networks than I have).
I have read reports of good success with using the relatively low cost Ikea router (called repeaters, but that is a debatable proper name) spread around their installs to extend the the strength and range of their networks. This makes sense to me to have several properly placed dedicated devices to be the ‘core’ router backbone of your network. Zigbee devices are going to select how they route back to coordinator and between devices on their own, you have no say in the matter. But, the devices often make their choice based on the signal strength and quality of neighbor devices. So if you seed a strong backbone, I think you are doing your best to build up a solid network. The reason to use a ‘dedicated’ device for these backbone routing functions is that you can power cycle them without effecting attached power units, and if needed you can move them to change your network topology.
I would take the time to read through as many of the threads on zigbee experience as you can, lots of useful experiences to learn from.
Do study the interactions between devices from different vendors. A lot of thread on this forum and the Zigbee2MQTT forum. Problems in this area seem to have caused a lot of headaches. You probably will have devices from multiple vendors, not much choice. But some do seem to cause more headaches.
examples of useful threads:
https://community.home-assistant.io/t/some-lightbulbs-drop-off-tradfri/273237
https://community.home-assistant.io/t/zigbee-and-home-assistant-is-driving-me-nuts/266256
Good hunting!