I also wanted to use a variety of colors to see if they reacted differently in similar circumstances. I used Prismacolor pencils.
I blended the same color with the same blending medium on all cardstock consecutively. So I started with yellow and did all the yellows with Baby Oil and so on.
Top left - Georgia Pacific
Top right - Recollections 65lbs
Bottom left - Neenah Classic Crest
Bottom right - Recollections 110lbs
On each card:
Left - Gamsol (low odor artist thinners)
Right - Baby Oil
I completely expected to say all the cardstock pretty much acted the same. Well it didn't. And I am definitely not a cardstock snob. If it is cost effective and works, use it.
I would be okay with using any of my cardstock for this technique. I did find that if I wanted more intense color that I would want to use Neenah or Recollections 110lbs. Overall I preferred the Recollections 110lbs to work with. The color went on smoothly and easily and blended how I wanted. I was surprised there seemed to be a difference between it and the Recollections 65lbs.
Choice and reason
1st choice - Recollections 110lbs. I bought this strictly as a card base, so I was surprised at how well it worked and very cost effective especially with a coupon.
2nd choice - Recollections 65lbs. This was a close call with Neenah. The Recollections 65lbs was smooth and easy enough to color. It blended particular well with the Gamsol. Fantastic for the price.
3rd choice - Neenah. Oh Neenah, Neenah, Neenah... you were my 2nd choice until the red bled into the green with Gamsol. Now there are a few user errors on these but this was not one of them. Not worth the risk for the cost of the cardstock for me.
4th choice - Georgia Pacific. 1st if this is what you can afford it isn't awful, it just isn't my first choice (now). From the start it just didn't want to accept pencil color evenly. Then it seemed to pull with the blending solutions I didn't quite make it pill but I could have. It is usable but it could lead to a lot of frustration when experimenting with this technique.
My advice, if you have the cardstock already experiment. If you have to purchase for this the Recollections line is a solid investment especially with a sale or coupon. Hope you found this helpful.