Some of my photobuddies use Lee filter holders with Cokin filters.
The holders are a thing of engineering beauty and a pleasure to use - so that decision is easy.
But the price of the Lee filters is very off putting.
However, having seen the noticeable magenta cast my photobuddies get in their skies I would never use one or recommend a cheap grad.
My Lee grads are superb.
I went with the digital starter kit as it comes with a nice pouch and cloth; then added in a one more grad.
Hence I've only got two grads - both 2 stop, one hard and one soft.
That's a combination that works in nearly all situations
and I REALLY take good care them!