Personally, always the second. It is actually quite easy to memorize some common light value intensities in Lumen units. They're written by manufacturers everywhere.
This way, if you use common values, your lights will seamlessly blend, and nothing will stand out. You will also know when you're breaking something for creative reasons.
I also do not get the obsession with following F-Stops/Shutter for CGI work to set exposure. In physical realm, F-Stop and Shutter speed end up modulating exposure, but primarily affect depth of field and motion blur.
And those are almost always used creatively in photography.
Photographers in fact go to great lengths to decouple exposure from those effects, for example by using strong (up to 15 EV !!) ND filters so they can achieve strong motion blur independent of exposure.
Or inventing crazy techniques like 'Brenizer' stacking to achieve shallow depth of field in wide angle setup to get past the limitations of physical shutter size.
Remember, intensities of lights are mostly absolute, we only have one sun, but exposure is completely relative value, the less light penetrates the sensor, the higher you would compensate it.
There is no such thing as "F8, 1/16, ISO 100" for midday interior. Maybe it's cloudy day and the windows is 20cm2 and floor is black. There goes your setup.
Don't set your F-Stop, set your exposure, depth of field and motion blur. You can't set those effects unrealistically and the fact that you can achieve them independently, is amazing freedom of CGI, use it. Locking them in exact ratio might be helpful if you're integrating into exact filmed footage, but otherwise, you can liberate your approach.
ISO literally has no meaning in CGI if you aren't matching footage, it's the same as simple EV compensation. So might as well just stick with it, making life simpler with one less value and broadening creative potential as well as simplifying the whole setup.
Here is how I set my camera in CGI:
0) I start with some base lights, mostly it's Sun.
1) I set my exposure in "simple" EVs. I go up until the desired brightness is achieved. Simple.
2) I set depth of field until I achieve desired creative effect in my scene. It ends up being obviously realistic value: F8-F16 for various broad shots where I want just tiny natural blur at the end of my scene to soften the CGI look, and F4 for something like close-up vignette. But setting that value only affects Depth of Field.
3) If it's shot with motion blur (car trail, breezy tree) I set my motion blur with shutter.
Physically correct workflow can be creative and user-friendly. Not puzzle.
