When I purchased my first Tansu in 1964, I was in truth only looking for a cheap way to store shorts, socks and shirts in my new little Tokyo house. My landlord was appalled that I was using "a storage box" as a piece of furniture in a traditional Japanese house.
Assuming that the kind visitors to this site do not live in a traditional Japanese house, well decorated with "refined nothingness", constraints to Tansu selection should be few: limited to aesthetic sensibility, functionality and reliability.
The most important consideration in making a selection should be Tansu condition. Personally, I like the oxidized by age dull brown/black lacquer on Samurai chests from the Edo Period. Also, farmhouse cabinetry of unfinished woods now stained dark by the smoke of resinous pine charcoal from unknowable kitchen hearths over a hundred plus years. Here I find the Japanese concept of SABI well manifest.
Regretfully, in Western countries and even now in Japan, it is not uncommon to find "old treasures" that have been striped of their age for the sake of "greater suitability to modern taste". WHAT A SHAME! I say to you: accept the grime with the antiquity or buy a well made reproduction.
For function, the versatility of TANSU is hard to top. Not being originally furniture or equatable with most western counterparts, imagination is the only limitation. A kitchen MIZUYA for books and electronics in the library! A Samurai helmet box as a night stand! A chest on chest ISHO (clothing) KASANE, positioned back to back for use as a cocktail table! The only limitation for serious consideration is convenience. If you're an impatient person like me, be prepared to be occasionally frustrated by a sticky door or drawer on a damp morning.
Often after explaining techniques favored by TANSU makers, I am politely challenged as to the reliability of such apparent simple joinery. Invariably, craftsmen in attendance who have used Japanese carpentry tools spring to my defense. For the TANSUYA, reliability was assured by incorporating flexibility into his creation by use of very precise tools and suitable materials. In that the "box" he was crafting might be moved at any time, it had to be prepared to yield without breaking.
The TANSU you select might look to be falling apart or ready for the scrap yard. Or, it might just have learned over the years to "roll with the punches" that life has thrown its way.