HCC and All Things ESP
Batteries not included... yet
Despite Dallas 1-Wire still being the most reliable wired sensor hardware and XBee family being most reliable wireless (both being supported as first class objects, see owapi-reborn and xbee-api-reactive), ESP* based solutions are probably the best bang for the buck today. Especially given the fact that ESPHome provides a practically zero effort integration.
HCC already supports ESPHome components, with support for more coming.
On the picture: a PCB for Wemos D1 compatible boards, with connectors for I2C and 1-Wire sensors, plus external data connector, and a NeoPixel (knowing status comes in very handy).
On a Tangent
"Whatever you cannot measure, you cannot improve". We can measure a lot of things all right, but making sense of massive data streams is much easier when they can be visualized.
There's a dedicated project, esphome2influxdb, to solve just this problem.