All of the dynamo hubs we sell are great, but I (Will) use these Shimanos most often because:

• The connector is super easy to use. It's a plastic plug that you poke the wires through and bend around this elbow inside. Even typing that out makes it seem harder than it is. I find the Schmidt's spade connection user un-friendly, especially if you have to take your wheel off a lot. They're hard to pull off and push on. They have a co-axial magnet thingy now, but I haven't tried that yet.
• I trust Shimano to make a bike part that'll work really well, even if it lacks some of the panache of the more expensive stuff. Yes, this isn't a great looking hub, but it's not bad. If you're getting nervous about how much you're spending on a build, going with this Shimano hub instead of a Schmidt is a great way to save $200 and not lose any functionality. Actually, you'll get the benefit of the Shimano plug, and your wheel will won't be as shiny desirable to thieves.

All dyno hubs have drag, especially when you spin the axle with your fingers, but while riding I haven't noticed any more or less when using any of the ones we sell. I know the Schmidts are supposed to have the least amount, but when you're out there riding, it doesn't matter. They're all almost imperceptible.