UniFi or Eero?
Eero is simpler and a good choice for a small home with no wiring. UniFi gives better coverage control, real switching, wired backhaul and integrated cameras, which matters in larger homes — at the cost of more setup and more decisions.
Choose Eero if
Your home is compact, you want it running in fifteen minutes, and you have no plans for cameras, racks or wired drops.
Choose UniFi if
The home is large, multi-level or hard to cover; you want wired access points; you want cameras with local recording; or you want to see and control what is happening on the network.
The honest trade-off
Eero hides the network from you, which is a feature until something is wrong. UniFi shows you the network, which is a feature only if the physical install is right. Either way, one Ethernet run to a second coverage point improves things more than the brand choice does.