I've come to find it depends on what you want to achieve, on two main factors:
1 - long term, or short term aging.
Long-term storage (like 10+ years)? Not too much, maybe a 3 or 4. Less air movement helps things to age and "marinate" better perhaps / it's believed.
Short-term aging (like a few months to only 2 or 3 years)? More like a 7 or 8. More air movement helps moisture and various compounds in the cigars mature and age a bit quicker. That said, it could also lead to a lessening of the effects of oils in the tobacco, and "force aging", at the hinderance of long-term performance of the cigar.
And,
2 - storage environment / humidor construction.
If you have a coolerdor, or something more low and wide? Not too much importance, same score, maybe a 3 or 4. Opened very rarely, not a huge elevation difference from top to bottom (moisture / RH is different in "layers" going vertically).
But for a big tall display cabinet, good air circulation is super important, I'd say an 8-10. If you open the doors a lot, if the seals on the doors aren't the greatest, if it's a tall cabinet, etc. All reasons why your moisture / RH can vary wildly from top to bottom. A really good fan / circulation system helps with better RH recovery, and helps to keep things consistent from top to bottom.
My thoughts, anywho.