I have ............
KOOD ND4 soft and ND8 soft (2 & 3 stop)
LEE 0.9 HE and LEE 0.9SE Grad (2 and 3 stop)
in the past i had 100mm Hitech (they were the original ones) and cokin Z pro 1,2 and 3 stop grads
The koods have a minimal blue cast but its easy to get rid of, MUCH easier than the horrible purple cast of the hitechs or cokin, especially when stacked.
I am a bit colourblind and the cast off the cokin and hitechs was a big no no for me as i struggled to see the cast to remove it in post.
The Lees are completely neutral, i dont have to worry about any colour cast at all so for me its worth the extra cost.
I have a hitech firecrest 10 stopper and looked at getting a couple of the firecrest grads but the price of them is even more than the lees.
The kood ones are great if you're on a budget.
One thing i would say though, dont buy a cheap filter holder, it'll do your head in, the lee foundation one is invaluable IMO