I've found that it's difficult to choose the best neutral-density graduated filters without comparing them in person. For most of us, this is not easy to do. To help rectify this problem, I'm illustrating a selection of various brands and types of filters: a "field guide to ND grads". While I own several of the filters shown here, other illustrations are possible due to the cooperation of friends who have kindly supplied photos of their own filters to me. Because of this variation of sources and photographic media, please note that this is NOT intended as a reference to specific filters' color casts, or lack thereof. Instead, it's intended to illustrate the type and extent of gradation within a specific filter. For example, there is a lot of variation in "soft" grads in that some will have a long, slow fade through the area of density, whereas others are intermediate between the latter and a "hard" grad. Which to choose? You might have different needs according to different conditions.
Below you'll find links to photos of various filters. If you have types or brands that I do not illustrate here, please contact me; I'd like to make additions to this "field guide" whenever possible. I'll mention in advance that I don't wish to include Cokin "neutral" grads in this comparison, since it's commonly known that they are in fact not neutral, instead giving an unnatural purple cast to the scene being photographed. Because of this, I cannot recommend their use and don't wish to include them here.
Hi-Tech 3-stop hard and 3-stop soft