Ultimately, what is more important; humidity or airflow??

[ColoradoBirddog]

So I've got a number of my tropical orchids in a 75gal tank. I'm running a 400w HPS over it. For humidity, I've got 3 inches of hydrotone pellets and water, as well as a reptile fogger. Temp is routinely 80-85°.

Currently, I'm running 2 smallish fans. One inside the terrarium, the other on top drawing in fresh air. The rest of the terrarium is enclosed with glass.

If I stop running the top fan, I'm able to get the humidity very high, at least in the 70-80% range. If I run both, I can keep the humidity in the 50-60% range, sometimes higher. But, often it drops as low as 30%. It takes a little bit of watering to keep over 40%.

So, ultimately, which is better for the orchids? Higher humidity and less airflow (but still some), or higher airflow with a little lower humidity?