I would recommend Nikon's 17-35mm f2.8 as an excellent wide-angle zoom lens for underwater work. I have used it for years, without any diopter, in domes of 8" (Aquatica) and 9" (Seacam). I recently bought the 14-24mm and shot a test roll with it using an adapted Aquaatica 8" dome on my Seacam during a recent trip to Bali. Now that Seacam has modified their 9" dome to allow use of this lens, I expect to use this lens much more in the future. But I do not expect that it will replace the 17-35 as my favorite wide-angle lens.
My basic take on the two lenses, relative to each other, is that if you need every nth degree of wide coverage, go with the 14-24. But be sure that your housing manufacturer has a dome that can accommodate the big diameter of this lens. Overall, however, the 17-35 is a much more versatile lens. It focuses several inches closer, which makes a significant difference underwater because you are focusing on the virtual image formed by the dome, not the real subject. The closer focus and 35mm short end of the 17-35 allows you to focus on and fill the frame with a subject almost half the size of that possible with the 14-24 at 24mm. At the wide end you gain only about 7 degrees additional angle of coverage (on the horizontal long side of the frame) with 14mm vs 17mm. Additionally, the 17-35 allows the use of standard 77mm filters while there is no practical way of attaching any filters to the 14-24mm lens. Most housing manufacturers already have a zoom gear available for the 17-35mm.
I can't say who has a manual focus gear for either lens as perhaps only Seacam has two lens controls on their housing, whereas most others (Subal, Aquatica, etc) have only a single lens control which means you have to choose between having a gear for zoom or manual focus. And most photographers choose to have a zoom gear and rely on auto-focus for focusing.
Because I really value manual focusing with a wide-angle lens, and most other lenses as well, I shoot Seacam. And have worked with a good machine shop to make make both zoom and manual focus gears for almost every lens I use underwater. Including both the 17-35 and the 14-24.
Fred