I use both Quilted Northern and Cottonelle. So...I buy whichever one is on sale, and look for coupons. I do well at the local pharmacy stores too - RiteAid, Walgreens, and Eckerd.
I also check their websites...
Northern website currently has a coupon link. You can get coupons for napkins, paper towels, and toilet paper:
http://www.quiltednorthern.com/products.html
Cottonelle website only has a coupon for their wipes right now -
http://www.cottonelle.com/specialoffers/coupons.asp