[darkclarity]

I think the best power supplies are those commissioned by big manufacturers to go with their hardware. The HP Touchpad's power plug being a good example. These brands don't want a poorly designed adapter killing their products.

[manyxcxi]

I was going to say something similar. I often use USB power supplies that came from old phones/laptops for my various little robot/gizmo projects. I do this with the (naive) assumption that If I'm Apple/Dell/Samsung/etc. I don't want to taint my products because of bad power supplies.

Other than using my non-pro knowledge and tools to roughly test voltage stability, sustained amperage, and output voltages on some of the power supplies, I don't have any hard evidence that this is true- but if I'm choosing between an Apple USB power supply or a no-name power supply from Amazon for a project, I'm taking the Apple one because I can assume it's a minimum level of quality that's good enough for my use. I've got a couple of iPad USB power adapters that I guard pretty closely because the other USB power supplies I have that say they're good for at least an amp or two are from no-name suppliers.

[NoGravitas]

My (Asus) Nexus 7 charger died, and none of the cheap replacement chargers I found would charge my tablet. Bought an HP Touchpad power plug off of eBay based on an XDA Developers recommendation. Worked perfectly for years.