The softness or hardness will depend on your impact and what you are trying to do.

This will differ for everyone.

I can say from my years in Korea that the old school coaches who trained their players for lessons, use a low spin, high speed, close to the table game to develop.

The coaches would right away go for OFF++ blades (think Schlager Carbon and blades of that class) with an older Tensor medium firm sponge (Yasaka Extend HS) that is medium fast and control oriented.

Such a setup made it SO DAMN EASY to bang bang back and forth close to the table with only a little spin... given that the player impacted the ball at the right part of the strike zone and the ball was at least net high on the rise or at peak. Coaches would drill the dog-crap outta that stroke and very quickly, a player would have a strong at the table rally game. (but would utterly suck at most everything else like receiving serves or serve or topspin vs underspin) (but what the heck, so much to work on and you gotta start somewhere, Koreans believe base form and stroke and footwork before the other stuff)

So... depending on how you hit, you could use a lot of stuff.

Personally, I find for a counter-hitting game close to the table, it is damned difficult to beat and All to ALL+ wood blade with modern control oriented rubbers in the sponge softness a player prefers. (I prefer a softer almost FX softness, many prefer and EL or harder softness)

Why?

That ALL blade and control rubbers allows you to hit harder and get into the topsheet/sponge without crazy rebound... that all contributes to landing the ball at higher percentages when you are close to the table and go for more power.

With enough time and training, one would learn to adjust the grip pressure to grow touch with a faster setup and still land it. (assuming one gets all the fundamental stuff right... and it is damned difficult to do that alone without coach or effective training)