A bit over a year ago I went to Japan. Ah, how I miss it, and the world in which travel was trivial, or at least not life-threatening.
In honor of that, and the central air hear breaking tonight, let me extol again the Best Air Conditioner: ductless mini-split.
Quieter than central air!
Just as personally controllable as a window unit!
Just as energy efficient as window if you don't want to heat the whole house! (Maybe more so, easier to seal against leaks.)
Can be put anywhere with a bit of drilling, so more flexible than window units that really want a particular kind of window!
Plus many models come with a reversible heat cycle, so you can use them for heating. Resistive heat would be expensive compare to natural gas heat, but I think a heat pump is comparable -- and if you're lucky enough to have green electricity, better for the environment.
Disadvantages: expensive, and if you're renting an apartment you can't just slip it in.
But still, awesome, and ubiquitous in Japan, and common in Australia.