Boveda makes humidity packs in four levels intended for cigars: sixty-two, sixty-five, sixty-nine, and seventy-two percent. The sixty-two-percent pack is niche, used mainly for very dry-profile aging or specific tobacco varieties; the working choice is between sixty-five, sixty-nine, and seventy-two.
Sixty-five percent gives the cleanest burn, the longest ash, and the most clearly expressed wrapper flavour. The case for sixty-five rests on the observation that lower humidity reduces the moisture in the wrapper, which means the burn runs more evenly and the smoke comes through the cigar without the wet-blanket effect of higher RH. This is the level I keep my own humidor at, and it works particularly well for long-term aging of premium cigars.
Sixty-nine percent is the middle ground that Boveda itself positions as broadly preferred for premium cigars. It is more forgiving of small fluctuations, more comfortable for cigars that arrived from drier shops, and produces a slightly fuller-bodied smoke than sixty-five. For new humidor owners, sixty-nine is the safer default.
Seventy-two percent has its uses but they are specific. Drafty humidors that lose moisture quickly, very dry rooms (winter heating, desert climates), or short-term recovery for cigars that arrived dehydrated. I would not run a tight-sealing cabinet at seventy-two for ordinary storage.
The full case on humidity, including the 70/70 myth and stability principles, is in How to Rest a Cigar.