Peter White has several (mostly higher end) lighting options and some good articles comparing lights. Great for information and comparing options. Very educational. Cool article comparing light output and beam patterns. (Something I wish I had thought more about before getting my present light.)

http://www.peterwhitecycles.com/lightingsystems.htm

Bottle dynamos are nice if: (a) you don't have a dynamo hub, and (b) you only need power sometimes and/or you have it as a backup for a battery powered light. Personally, I am very unthoughtful about charging or replacing batteries, and I tend to end up somewhere in the dark with dead batteries. That's why I like dynamos.

I have a Lumotec N paired with a hub dynamo. You can switch off, but I can't see why you would ever want to, unless you're trying to sneak around. In which case, your target will hear your IGH hub pawls ticking. The beam of the Lumotec is acceptable, but not super great.

If purchasing again, which I am about to, I would get one with a standlight (capacitor charges up and keeps the light burning while you are stopped for a few minutes).

Like many other things, I think the rule is that you can have cheap, elegant, and effective. Choose two.

Eric