Z-wave products seem to have a minimum 45 euro price tag no matter what you buy. But they have my preference due to the fact I can set associations that improve reliability, even when Homey’s not working. Zigbee can do similar things, just not with Homey as the main controller.
Fibaro’s proved very reliable to mee, Qubino too but I have way less of those.
As for Zigbee smart plugs: Innr sp120 are not so reliable for me, had no sp220 for the lack of power measurements so I cannot tell if they are any better. Hue smart plugs on the other hand are very reliable, but bulky (cannot fit two side by side). I have one dimmable Hue bulb, so I cannot say how reliable that will be
Homey has limits with regard to how many zigbee devices it will support nicely. When using Hue bridges, I see topics here that having more of those may cause high load on Homey. This leads to delays inhandling flows, so that might be worth investigating.