Here's what I know...
Hub vs Rim dynamo
I personally don't find any reason to go with a rim dynamo. Many of the advantages go away - you can't leave a rim dynamo on your bike without the change of it being stolen, when it's on it has more drag than a hub dynamo, and it can have issues if your rim gets wet or icy. While there are a few interesting things about them, having a rim dynamo largely negated the convenience factor which motivated me to get a dynamo in the first place. Most people (not everyone, but most) go with the hub dynamo.
Which Hub Dynamo
Sanyo H27 - $135 for a prebuilt wheel. Cheapest version. Rolling resistance when on is similar to the Shimano version, rolling resistance when off doesn't really change (unlike the Shimano version). It's a little lower quality in general vs the Shimano hub, I've read more about it giving vibrations while riding and such.
Shimano 3d-72 - $214 for a prebuilt wheel. Rolling resistance similar to the Sanyo when on, but much lower when off. Note that by "much" I mean relatively speaking - I have trouble telling the difference when actually riding the bike. The Peter White site lists out the efficiency, and there was another article somewhere on it to. It's also a little higher quality hub overall vs the Sanyo.
Son28 - $380 for a prebuilt wheel. Very slightly more efficient than the Shimano. Supposedly more serviceable, but I don't really know if it is or it isn't. Since it costs almost twice as much, and only has slightly more efficiency, I don't think it's worth it unless you **really** ride a lot. Since I've never had a front hub wear out, I went with the Shimano.
So basically it's between the cheaper Sanyo or the more expensive but slightly nicer Shimano.
This is where my prices are from, they're similar to the prices I've seen everywhere else -
Custom Dynamo Front Wheel
Which Dynamo Light?
If you're road riding (any sort of flattish trail, any riding that's not mountain biking through the woods), in my opinion, there's only 1 choice - the Lumotec Cyo premium ($110). There are cheaper lights but I think the extra cost is worth it. There's 1 light that's more expensive, but I don't think it's worth it - you get 10 more lux (80 vs 90) but it costs twice as much. The Lumotec Cyo Premium, imo, is the best cost-benefit ratio.
Now - if you're touring, or need usb charging, there's also the Lumotec Luxos IQ2. It provides usb charging from the hub, which is nice. But it's drawbacks are:
- It's much more expensive ($250)
- It's large - about 4 times physically larger than the Cyo Premium
- At least one poster here had both and thought the beam pattern on it was worse than on the Cyo Premium (that's just one opinion though)
The B&M (same company as makes Lumotec) E-Werk is a seperate device that provides usb power via the dynamo as well, it's $144, so the Cyo Premium + E-Werk cost is almost exactly the same as buy a Lumotec Luxos IQ2.
If you're mountain biking, there are other choices of lights that don't have a cutoff, but I'm not as familiar with that, and I won't go into it as it sounds like you're not mountain biking anyways. (Difference is, the road lights have a cutoff like a car headlight, which imo is a really great beam pattern for biking on the road - I say this from experience riding with a Cyo and also riding with several different battery lights. A mountain bike dynamo lights uses the traditional round beam, which is better for illuminating twisty turns and low hanging branches, but worse, imo and experience, for someone riding on the road.)
So basically, for the hub - it's Sanyo vs the Shimano.
For the light, it's Cyo Premium vs IQ2.