Check out the cost. Not sure that the cost of getting the right concrete blend, then polishing and finishing is much less than a good quality engineered timber floor??

To answer your original question- it is a matter of taste and where you plan to use it.

We will be having polished concrete in our main entertaining area- kitchen/dining. We then have stacker doors opening out to a small patio (same concrete, different grind) then courtyard. I chose concrete over timber for maintenance and durability. We love entertaining and have a big family. I really don't care to fuss over scratched timber boards due to 30 people tramping in and out of the house, along with the scratches my dining chairs have made to past timber floors. There will be expansion joints to reduce cracking, but I'm not fussed about that too much as I think it adds to the character. I'm not looking for a terrazzo finish.

It is a north-facing room that will get full morning sun through the stacker doors- so we are hoping (fingers crossed) to get the thermal mass benefit of concrete also. If not, we are running cable through it so we can heat it later if needed.

We got our engineered timber floors from Harmony Timber floors on the Gold Coast about 12 months ago for $120/m laid and glued down. Yes, the top layer is at least 5mm and is real hardwood, attached to a thick base of ply.

The hardwood layer goes down to almost the T&G.

We are using Metromix (Able Concrete) in Sydney, not sure where you are. We've chosen a really lovely light coloured concrete and lighter aggregate (Bondi Pacific with snow oxide)

Selecting a polished concrete floor finish is a decision that goes far beyond the look and feel of the surface. It is part of a holistic process and part of a system that delivers a sustainable outcome. the floor finish should not be seen in isolation but in combination with window, wall and ceiling design. Properly considered it should deliver a cool internal space in summer and a warm space in winter when the sun is shining. The property that a polished concrete floor encapsulates is that of thermal mass. A tiled finish over concrete will deliver the same outcome. Other finishes will be less efficient in this regard. It is better to make decisions based on performance if you want your building to reduce energy costs. Aesthetically, polished concrete offers enormous variety in colour and texture dependent upon the choice of cement, aggregates and degree of grinding (level of polish)