I've been buying the store brand, some are quite good. Recently tried the Rasin Bran Crunch and I also really like their version of Honey Bunches of Oats. I try to pay about $2.50/box and it's gotta be on sale.
I noticed on my last shopping trip that the 11oz size 75% less sugar Trix was the same price as the 14 oz size store brand cereal I bought.