None are very good. A few have installed banks of charging kiosks...a few others have those little towers with dongles hanging off of them.

A couple years ago, I started carrying external battery packs. This one has worked extremely well for me for almost a year now. Handles cell phones and tablets well. (Thankfully, I haven't needed to charge a laptop in an airport in a long time, although I know people who carry heavier battery packs for that purpose as well.)

I also seem to accumulate those very small charging sticks that are commonly given away and conferences and such. They look like this. (Note: they're worth about ten bucks max. The fact that Amazon lists this one as $70 and 70+% off is kind of a joke.) But the ones I've had fall apart quickly and don't seem to deliver the charge they are advertised to. Still, for a short trip I might just throw a couple of them in my bag since they are super-light.

In other words, I've liberated myself from airport power outlets. The situation is dire and I don't see it getting a whole lot better anytime soon.