One thing an airport has to be is fit for purpose. What makes a good airport for a long haul transit hub is going to be different to a short haul /domestic hub which in turn would be different for end of the line airport.
I think efficiency above all else. But otherwise, in addition to many of the items mentioned
1) Noise dampening - with the large hard-tiled monstrosities that modern airports tend to be, many of them are insufferably noisy (BKK - looking at you). A good airport has features that will dampen that noise (look at SIN T3 - it can be incredibly busy but still relatively quiet - in addition to carpet in many areas, there are also other design features that help contribute to noise dampening).
2) Intimacy - SIN and perhaps HKG to a lesser extent are both large airports, but still seem maintain a sense of intimacy . DXB on the other hand, like the city it serves, is big and glitzy and not to my taste at all.
3) Airports that have a good range of shops but don't feel like a shopping mall with an airport attached. In Europe for example - the likes of CPH, MAN and LHR just seem like giant shopping malls, whilst ZRH seems to maintain more of a balance.
A diverse range of airports I actually like that meet the fit for purpose criteria well includes LCY, ZRH, SIN, HKG, ADL, USM, OSL, amongst others.