The Blender devs are crowdsourcing HDRI images to bundle with 2.8. Pablo explains details in the video below, and you can find the full details on the Blender Devtalk forum.
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I think hdrihaven.com has the best HDRIs and with license CC0
If Blender Devs want to bundle HDRI to Blender software, then I think it is not a good Idea, 1 or 2 HDRI is good, but more makes Blender unnecessary bigger, better would be in blender choosing a directory for local HDRI images of user choice, not lightstudio directory, should be an option for lightstudio directory in preference.
A few studio templates would be nice to use as a starting point, for combining or as a placeholder. They don't have to be highres.
Example of a basic HDRI set (~7 HDRIs):
- 2-4 regularly placed light panels
- Floor Gradient
- Green grass+blue cloudy sky (general purpose for archvis, similar to the WinXP wallpaper)
- Sunset (think 'Golden Hour')
There is also this addon which allows you to make studio lights and custom HDRIs https://blendermarket.com/products/hdri-lighting-studio--editor