Watsen are the ones that most people agree look the best, but they aren't cheap and take a while for delivery as from canada
I suppose it all depends on your personal taste and the look you're going for with the bike. I got some from eBay, made in China, low price but fit the space and give off good light.
As Tom says the cheapy chinese ones do fine. Watch out for the ones that don't have a stud to pass though and instead rely on sticking them to the fairing. Personally I swapped mine out for some Oxford Nanos as the flush fits can be hard to see.
