I bought Koh-i-noor out of options on store on graphite pencils but it was quite disappointing. They felt a little cheap to use.
Sometimes my HB scratched the paper or even left blotches of graphite. The tone gradation was not easy to obtain. Coverage was just hard to do smoothly.
Now I bought a lost batch of US Prismacolor Turquoises (which are not made anymore, they are now made on Mexico) and they feel much better and behave amazingly.
Pencils take a great deal on the final result, and I think it's a good thing to use the best materials you can get to work with.
And of course, it improves the fun factor a hundred times!