The best place to assign static IP addresses is always your DHCP server, which is usually your router. This ensures it won’t assign that address to some other device, and provides a central location for you to consult when you need to know which addresses are in use.
I would only resort to setting IP addresses on individual devices if it is not possible to do so in the DHCP server. This might be necessary if, for example, your device is running the DHCP server.