ESP-8266 Development Board (NodeMCU, ESP-12F)
This NodeMCU V3 compatible module carries an ESP-12F module, which contains the now famous ESP8266 Wifi system-on-chip. You can program this in Lua or flash it from the Arduino IDE.
It has an on-board CH340G USB-to-serial converter, so you don't need an FTDI cable. It also plugs straight onto your breadboards once the headers are soldered on.
If you didn't need the ESP-12F you could also look at our other NodeMCU board for a more cost effective solution.