I have found that Boveda Packs are the most effective and stable form of humidification in most humidors, coolers, and tupperdors. These are what I personally use and recommend.
I have found 65% to be the best option for my area and smoking preferences. For that reason, that is the RH I use for the cigars I smoke and the cigars I sell. That is also all that I have on hand right now. However, as I grow I may begin incorporating more sizes and RHs. If you have a request, let me know!