IMO - if you're needing to buy online, definitely give the Gina K. Designs Pure Luxury cardstock a try. Both the white and the ivory come in two weights - an 80 lb. "layering" weight and a 120 lb. "base" weight. Both are fantastic with a very smooth finish. The white is a lovely bright white. I tend to use the 120 lb. for card bases, whether I'm making a one-layer card or if I'm adding several layers of cardstock and/or designer paper. I use the 80 lb. for stamping or printing images to color.
I don't work for Gina K., but I've used a lot of her cardstock for cards for Operation Write Home.