I've been using the highest level shimano ones for a few years, the DH-3N80 is supposed to have "ultegra level" bearings and it's also got an aluminum axle. There is an LX dynamo that is almost the same (cutouts, etc) but it has a steel axle. I saw the LX one on ebay for 72$ it seems like the best value right now, I almost snagged one even though I don't need it. The 36 hole versions of the shimano dynohubs aren't as common but usually available online from Europe. I haven't used a SON hub yet but I'm not fast enough to care about a few% efficiency. Peter White's site has some detailed information on both the SON and Shimano hubs, check his site out. I love my B&M lights, been using them on rando and commuting bikes for a few years and they seem like the best value when compared to the more expensive lights.