I mean it completely depends on what you want to do. If you’re simply looking to control stuff via your voice regardless of amount of devices, Google Home or Alexa would both be perfectly fine. It’s when you start looking into automating your smart home devices you can get much more in-depth flexibility with other platforms.
I have around 80 devices and use Home Assistant so I can set up complex automations with various conditions.
You cannot just buy a hub like deCONZ, ConBee, Sonoff etc and it just magically work with homekit. If it isn’t homekit certified it will not work without something like home assistant or homebridge as an intermediary.