Also Raspberry Pi (the Coke to Arduino's Pepsi). More expensive (especially since hoarders have been bulk ordering them and jacking up the price), but IMO more flexible and powerful.
There are several others, but Arduino and Raspberry Pi seem to be the ones with the widest variety of "it just works" add-on components and programming tutorials.
https://www.raspberrypi.com/
There are several others, but Arduino and Raspberry Pi seem to be the ones with the widest variety of "it just works" add-on components and programming tutorials.