Oh filters.
I have a love and hate relationship with them. the purist in me likes using them. but I often find blending of multiple exposures works better.
I own a hitech holder, and hitech filters, 1 to 3 stop soft gnd, and a 4 stop ND. The 4 stop is cool to force long exposure.
The reverse one is great for sunset/ sunrise shots, when son is on the horizon. I however find a lot of times the light transition is not a simple light, and though I carry my filters, very often I end up with multiple exposures.
I couldn't imagine shooting landscapes without GNDs. I use a 3 stop soft and a 2 stop hard, handheld Hitech Cokin Z size filters. I think those are really the only two GNDs one could ever really need.
I used a 0.9 density Singh-Ray Reverse GND on a trip to India and got some decent results, but not when the horizon is not exactly demarcated. Recently I sold it because I found I wasn't using it much these days and would rather do HDR with AEB when I need to.
I use 1-2-3 stop soft & reverse Singh Rays. I don't have a favorite - I attempt to choose per meter readings and practical experience & sometimes multiple filters for additional stops. I also do some blending but still practicing to "perfect" that technique. I enjoy playing with my filters in the field more than sitting in front of a monitor doing PP. I voted for 3-stop reverse as a default choice.
