I bought Adafruit's ESP8266, and I was lucky enough to get an RPi Zero.
The latter I really like. $5 + a $7 WiFi dongle + cell phone USB power source = 1GHz Linux computer.
I started with HDMI and a USB hub connected to keyboard/mouse.
Installed VNC so I could get rid of hub and go "headless". Works great via WiFi.
I then installed SMB and auto-mount of a file folder on my NAS. So the RPI has many GB of storage via WiFi.
This works very well. Small size, cost, lots of programming languages not crippled as are the Python and Javascript implementations for STM32F ARM boards (I have those too).
The ESP8266 boards... cheaper. Are not good in many ways, in my opinion. Having used it, I much prefer the RPi Zero.