"Is it better to have a higher or lower rh% for storage for, say, 6 mos-1 year?"
As a matter of practicality, no -- stable temp & RH w/in the desirable range. I probably posted I prefer a max of 75%, so if my "go-to" storage is tending to lose humidity, I don't have as much trouble maintaining 65-70. Higher humidity does risk mold problems if there's a humidity spike in your storage unit[s]. I think as others have posted some tobacco smokes/ages better toward the drier end of the "ideal" range & others toward the higher.
For long term, visit occasionally, but don't disturb too much [ie daily]