Waterfalls are one of my favourite landscapes to shoot. I am only going to comment on #2 and #3 as #1 is the same shot as #3 with some different processing - prefer 3 to 1.
#2 - image is a bit cluttered and I would like to see more of the actual falls as a lot seems to be hidden behind the fern. I am not sure what that silvery-grey thing is in the top half, but I would have lowered my camera a bit to exclude it, or cloned it out. It is a distraction. Also you need to watch your exposure as some of the water in the middle of the falls is marginally blown out. You may be able to correct this in post, depending on the software you are using.
#3 - again, I would like to see more of the falls as some of the water below the falls is "cropped" out. The water below the falls is badly blown out - all the detail that should be in it is gone and probably not recoverable in post.
Just a couple of general comments - you have to decide what your subject is and try not to include anything that doesn't support the subject. You didn't say which ND filters you had acquired, so it is hard to suggest how to expose for the blown-out water. Let us know the details of what they were and the exposure data and perhaps folks here can offer some suggestions about how to improve on what you have presented.
Hope this helps.
WesternGuy
