There aren't many Android TV boxes you can plug into your TV, but there are a number of TVs with Android TV built-in. Sony makes a well-reviewed 49-inch TV with Google's software, and you can get a good deal on it today, assuming you want to buy some stuff from Dell. Pick up the TV, and you can get a $300 Dell gift card.
The TV (XBR49X900E) retails for $950 most places, and the Dell price is only a few bucks cheaper at $947.99. However, that's not the "deal" part of the deal. Buy that TV from Dell, and you'll get a $300 gift card to use on Dell's store. The code will arrive in your email inbox within 20 days of buying, and you need to use it within 90 days of that.
As for the TV itself, it's a 4K set with HDR support. It's one of Netflix's recommended TVs, too. The Android TV software gives you access to all the usual streaming apps, along with Chromecast support. It has 4.2 stars on Amazon, and Rtings gave it an 8.2/10. You can't use the emailed gift card on the TV, obviously. If you get the gift card code fast enough, there are more sales to be had at Dell right now.