We do not make absolute win-or-lose comparisons, because these are different product categories with different use and feel. If you want bedding you can fold and store, lay on a firm flat surface, and sleep on in the Japanese way, a shikibuton is a sound choice — judge it by your own feel, space, and budget.
Use this answer as a buying guide before choosing between HIMARI and SORA: compare feel, thickness, storage, available size, and whether you want everyday Japanese bedding or a fuller flagship shikibuton.
