If you do go with a FireTV device, I highly recommend getting this cheap adapter that allows for ethernet and multiple USB devices:
https://www.amazon.com/dp/B00LLUEJXW/?tag=aftvn-20
The FireTV performs much better on ethernet if available. If there's any way to run ethernet cable to your main device, it's absolutely worth it. But if not, make sure you have a good wifi router and one of the later generation FireTV devices, and it should be fine.
The reason you want extra USB ports is that allows you to use wireless keyboard/mouse or add external storage.
Note: The referenced adapter does not work with the Gen1 FireTV Stick. You likely won't find one of those really old devices, but I thought I should mention.