Suggest platform

I’m here to ask for some suggestions on the development board choice. I’m fairly new to this field and a wide range of different chips from different vendors is a bit overwhelming.

I am looking for:

) hopefully a development board

) 802.15.4 compatible

) low power consumption

) will connect accelerometer, piezo sensor, capacitive touch sensor

) small to fit on the palm of a hand

What I am trying to achieve:

) battery-powered node

) on high readings from sensors sends to the base station

) hopefully sleeps most of the time

) distance up to 20 meters

Maybe you can point to your personal favorites that can be used to solve this.

Thanks!