These days, the only Android TV worth purchasing is NVIDIA's SHIELD TV. Earlier this month, we saw this box discounted to $140 on Amazon, but it's been even further discounted for Cyber Monday. It's temporarily out of stock, but Amazon is currently offering the SHIELD TV for just $118.99.
The SHIELD TV has a pretty long list of features to its name. Of course, it can do everything a normal Android TV box can do, but it can also act as a Plex server, a Samsung SmartThings Hub, and even a gaming console with NVIDIA's GeForce Now cloud gaming service. This version only comes with the remote; you'll have to buy the game controller separately to play games.
Oddly, Amazon still has the price at $139.99, with some text saying "Save an extra $21.00 at checkout" below. At checkout, you will see the correct $118.99 price. Again, these are temporarily out of stock, but you'll still be able to place an order. Be prepared to wait a bit longer than usual for this to come in the mail.