Which microcontroller and radio / bluetooth module to choose?

Question

Do it yourself

There is a miniature sensor, you need to attach the simplest logic and wireless communication to it, preferably Bluetooth.
The most important parameters when choosing are volume and energy consumption - the smaller the better.
Price also plays a role, but is still secondary. The speed of work is not significant either.
Any architecture will do, since I'm new to this, I'll have to learn almost from scratch.
PS By miniature I mean less than 15x15x10 with transmitter and battery.

Answer 1

ESP8266 - you will hardly find less, all in one chip.

Answer 2

arduino

Answer 3

Install from the HC-03 series ... HC-06
It's easy enough to work, you can easily friend both another microcontroller via bluetooth, and an android, there are just a ton of examples.
And the arduino mini controller. In my opinion, the most "simple" option is to get a more or less small device.