Best electronic cat door?

Okay, now that I live in Maryland, y cats aren’t allowed to run around freely outside anymore. I’ve been looking into electronic cat doors (like the ones with microchips and electronic collars and such), and I don’t really know where to start.

Which kind is the best, if you’ve had to deal with them? All the reviews I’ve seen are kind of mixed, so I don’t know what I should look into first.