I've used two brands, the Nikon DR-5 (works on D700 upwards) / DR-6 (works on D300 downwards); and a none-branded one off ebay.
Frankly, the ebay version, although much cheaper wasn't anywhere near as good as the Nikon ones. the build quality of the Nikon ones are just superb. I have a slight issue with the DR-5, vs. the DR-6, it's not as sturdy & harder to mount / remove; but these are not serious issues.
I never go out without them with me. For macro, landscape, nature, wildlife, you name it! I love shooting low, and this beats the hell out of getting my neck in a twist.