Long term storage of any auto should be in a relaxed state, with the kinetic spring energy dissipated,(released).
As far as non auto folders go, either way works, it all depends on how they are stored, and what they are stored with.
I collect a lot of older slipjoints, some of them have celluloid scales which can deteriorate rather rapidly, giving of a gas which will affect almost all steel if left in contact long enough, the same thing applies to storing blades in leather sheaths.
Basically, it all depends on what you collect, and what your trying to prevent during storage.
A little more specifics will get you more accurate answers.