Depends what you're willing to spend, proper Magicshines and the Fluxient lights seem to be better build quality than the cheap T6 lights and some models are much brighter, but the price reflects that a bit and the
ebay lights are great value. They're a bit like driving round will full beam on though especially in urban areas, so need to be mindful of the glare.
The light output of these Cree lights is mad, a friend recently bought the insanely powerful 3xU2 Fluxient, equivalent of about 4 T6 lights and side by side is brighter than a car's headlight on full beam!