This is an interesting topic since IoT is a very relative term.
As far as which language is best, IMHO, it really depends on what part of the stack your are looking at. At a lower level, closer to the metal, C and more recently C++ would be best as well as some sort of RTOS like FreeRTOS. But the further up the stack you get, you could be looking at Javascript, Python, Rust and even Flask on an OS like Linux or Windows 10 IoT.
Michael Barr put out an interesting post a few months back titled "The Rise of the Full Stack Developers" based an observation he made regarding the skill folks list on their LinkedIn page. Myself have seen Firmware positions that listed Javascript, Python and even Go as a requirement for the position.
jomoenginer , yes. And it's mainly the capacity of the controller/processor and resources - and the energy needs in some cases - that determine the language options.
unlimited processor umph, unlimited power, no energy restrictions (there are IOT devices that are tied to the power grid and have the resources of a decent server): any language can be used.
When you step down from that, the language options get narrower.
My point was more inline to understanding the full stack of an IoT deployment. Smaller memory and processor constrained devices will have their limitations, but getting that data from the sensor to a database, or web browser or even something like AWS or Azure takes multiple layers and different development environments. Looking at a good middle ground, Python is a language that fits nicely in the middle and is often used as the glue to get that sensor data to the cloud.
Sorry, but the thought of an an IoT device tied to a power grid seems like something just waiting for trouble.
