I use SON 28 (1998 & 2009 vintages) and Edelux.
I use dynamo rear lights (B+M Secula or Toplight line plus) because there's no point in an automatic "senso" front light if you have to stop to turn a battery back light on. The disadvantage of dynamo rear is that you've got the wire, which some people find unsightly.
The Edelux is fairly senso-tive, and turns on quite readily, to the point were it may be on all day in winter. I doubt I touch the switch more than twice a year.
Sidewall dynamos have the advantages of being cheap, light and of giving zero drag when not in use. They also have the disadvantages of being noisy, giving a noticeable amount of drag when in use, sometimes slipping in the wet (= no light), and can possibly damage your tyre. You've also got to stop to turn them on or off, unless you don't mind risking your fingers getting in the spokes (= no point in automatics).
Hub dynamos give an un-noticeable amount of drag when the lights are in use, and a smaller amount of drag when they aren't in use. They never slip, are silent, and there is no chance of tyre damage. The dynamo bit is not far off 100% reliable, leaving only the possible bearing problems you'd get with any hub.
Because the hub is always turning, automatic on/off is possible, and on/off switches can be put on the light or other places you can reach whilst riding.
The magnets try to hold the hub still in one of 26 or so positions, with the result that there is sometimes a vibration that can be felt though the handlebars. Some people (eg Wouter at
http://swhs.home.xs4all.nl/fiets/) have bikes that resonate at their normal riding speed and find this objectionable. I don't normally notice it.
There are normal wheel variants, which give power at a low enough speed to satisfy German regulations when used with a halogen light, and small-wheel variants that have fewer magnets because small wheels spin faster. You can use a small-wheel dynohub in a large wheel with LED lighting to get lower drag, at the expense of less light at slow speeds (going up steep hills) and less power available for your USB port or whatever.
The dynamo hubs that would be used by sports riders (with SJSC prices) are...
SON 28 - £160 to £260, depending on version
SON 20 (small wheel) - £170 to £220, depending on version
Shimano 3N80 - £100
Shimano 3N72 - £75
SP HB-017 (switchable) - £155
SP PV-8 - £90
SP SV-8 (small wheel) - £85
The power/drag performance of the hubs (within large/small wheel category) does not differ by enough to make a basis for choosing one over another
SON hubs have a 5 year guarantee, and have a pressure equalisation system to stop the contraction of air within the hub shell sucking water in past the seals. This may happen if you ride into deep water or fall off in a ford on a hot day, or go out of a warm house into cold & heavy rain. Servicing is by return to Germany via SJSC, cost about £50 when out of guarantee. SON hubs are available in a much wider range of options, and in some cases may be your only choice (eg for a Surly Pugsley or a Trice).
Shimano hubs have a 1 year guarantee. Officially the RH (connector side) bearings aren't serviceable. You can, but you may break the dynamo bit if you are clumsy about it. The 3N72 is noticeably heavier.
SP hubs have a 2 year limited guarantee (against manufacturer defects only). They aren't user serviceable, and currently manufacturer service means return to Taiwan (I believe). The HB-017 version has a switch on the side that moves the windings away from the magnets so there's close to zero electrical drag.
There are also a number of other dynamo hubs, such as the Shimano 3N30, that can be found quite a lot cheaper, especially on German websites. Generally speaking, these would be somewhat heavier, and give a small amount of extra drag lights on, and a larger amount of extra drag lights off. I'd consider that limits them to town bike use, but if the money is significant they are perfectly usable for all riding.
The best dynamo lights are generally either B+M or Schmidt (the Edelux is an upgraded version of the B+M Cyo). If you ride largely off-road, Supernova and Exposure make good, if expensive, front lights.
USB charging.
Neatest is built into the front light. You've choice of B+M Luxos U (£100), Axa Luxx 70 plus steady (£55), Axa Nano 50 plus steady (€55) (German prices from rosebike and bike-discount). The Luxos has the best & brightest beam, and a built-in cache battery that will continue to supply power for a while when you stop. How important the cache is depends on whet you have plugged in to the USB.
The other common option is the B+M USB-Werk (£55, Rose). This is a separate module that you would attach to the top tube. It's also got a cache battery, and is more reliably waterproof than the lights are. It can be run off a sidewall dynamo,if you insist.
There's also the B+M e-Werk (£76, Rose). This isn't USB as such, but is adjustable between 2.8V and 13.3V, and 0.1A and 1.5A so it's just a matter of setting it for USB. No cache battery.
Other USB chargers are available cheaply from
eBay or Amazon. The common problem with these no-name charger is that they don't handle excess power well, so if you leave them plugged in whilst the lights are off and you've no USB plugged in or it has stopped taking power because the batteries are full, the charger can burn out.
