Brand really doesn't matter. The main point of a basking bulb is heat output, so the real answer is - the brand that give you the right amount of heat! The only other requirement is that is be a clear, white light to offset the color of your UVB (assuming you use a florescent) to protect your beardie's eyes. As long as you put the bulb in a hood with a ceramic outlet, then there should be no problems at all. I personally prefer 60watt incandescent house bulbs, because their are a high enough rating to really do good things for dragon eyes, as well as put up a nice amount of heat.
Since they are so easy to find anymore, due to the fact they are inefficient and put out too much heat (but that's what I want!), I but them from eBay. 4 bulbs shipped for $6.
Really, they produce some of the best light I've seen!
Dimmers that are not built into the fixture (ones that instead go between the light fixture itself and the outlet) do put a strain on the bulb and can result in not-quite white colors. I personally find that it's easier to change the wattage around to suit my needs where it can be used at full strength, even if I have to move my cage decorations around a bit or mount the bulb higher up.