I think I agree that there really isn't a comparable competitor to rpi .. rpiZero W offers a lot for an iot module at such a great cost. maybe something like the CHIP, but not even?

I'm currently working on an agriculture sensing iot platform and going to try to use rpiZero W with the current spectrum sensor from nanolambda. http://www.nanolambda.net . luckily they have the rPi api,sdk already.