The bees knees! I, like many others here and elsewhere, have had great luck with the Shimano hubs, I think mine was a 3N72.

I bought a B&M light from Peter White (Busch & Muller dynamo bicycle lights), the 'Luxos U', which has a USB port built in. They are not cheap, $200+, but great since it's serves two purposes.

It wont charge AND light up, but did charge my Samsung S5 adequately, albeit a bit slow. I had Spotify running most of the ride rockin' out, seemed to maintain a charge. If I kept phone off without running apps, it would take most of the day to charge, but would get there eventually.

I am building up a new wheel and decided to try out the SP hubs since they are a bit lighter than the Shimano.

The newer bottle dynamos look cool too, but have never tried them.