i am biased having only used the 4 x 6 LEE filters. turns out for me, the most used filter is the 0.75 hard GND (sample below). i tend to shoot at the edges of natural light doing landscapes. I haven't had to deal with color shifts with this filter. 2nd used is my D Benson reverse 3 stop GND.


Brush Strokes by ernogy, on Flickr