Previously this list had the Moto E4 here, but the newer Alcatel 1X is a great cheap phone worth recommending instead.
The Alcatel 1X looks like a pretty standard boring phone, but you get a lot for just $99. That includes a nice big 5.3-inch 720p HD display, small bezels, plenty of power and a rear-mounted fingerprint scanner. Not to mention a fast and clean version of Android 8.1 Oreo and fast updates.
You'll love the soft-touch suede finish on the back next to the rear 8MP camera, and there's a 5MP selfie shooter on the front too. Not to best cameras, but more than enough considering the price.
There is a powerful Quad-core processor, 2GB of RAM, 16GB of storage, a microSD slot and a 2,500 mAh battery that should hopefully last all day. If you want a bigger screen or longer battery life consider the Moto E4 Play instead.