Prototyping IoT with Pi and Raspbian

If you are launching a product and are prototyping and piloting to your initial customers with Raspberry Pi and Raspbian, which needs would you have that are not already covered by Raspbian out of the box (e.g. development frameworks such as Node.JS, MQTT, etc.)?

Please list the top 2-4 type of tools during this phase and please be as specific as possible. Thank you and we hope to provide value to the Pi community with our FOSS project.
1.Most important capability/requirement(Required.)
2.Second most important capability/requirement(Required.)
3.Third most important capability/requirement
4.Fourth most important capability/requirement