For chocolate chips, cocoa powder...whatever you use when you bake. Just curious to hear about brands.
I buy Aldi chocolate chips (semi, white and milk when they have them) and I buy my cocoa in 50# bags from Dawn Foods. It is the best stuff ever!
Guittard for DP cocoa powder and couverture chocolate. Hershey's for my basic chocolate cake. Callebaut and Guittard for melting into batters and frostings or to use as chips in cookies. I have Pernigotti cocoa powder, but it's harder to get. Sharffenberger cocoa powder for all but the basic Hershey's cake. For my chocolate chip cookies, I use Hershey's chunks, but all other chunks are Guittard. Truffles are Guittard.