As for myself, I definitely like the newest digipak packaging of Hypnos CDs, "Out and About" by Herion looks really nice and it was very good decision to go this way, Mike. I am not a big friend of sleeve packagings, yes, you can save a lot of storage place, cheaper shipping costs, but the insert/artwork can be easier damaged during the shipping and without a spine it's more difficult to find even if well organized. And the final product is less attractive in most cases. But there are some exceptions, for example Faria Records packagings with cards or Amplexus with its sublabels, no spines, but these ones are closer to special collector's items than to sleeve only packagings. I am a collector, so I have to accept that my growing collection will require some extra space, I think you have to deal with this no matter what you collect. Anyway, here are the types of packagings in order of my preference:
Special collector's item
Digipak (all types, with spine)
Standard jewel case (also plastic case with spine, dataObscura as example)
Slim single jewel case (with spine, Practising Nature/Bluebox as example)
Slim jewel case (with no spine)
Sleeve/wallet (with no spine)
Richard