So -- First up is MAC because it's pretty much universally known. Think about what you have to buy only from that brand. Something you always tell people to get or stay away from?
If you have a "best of" (or "worst of") product please try to include an image of the product in your comment. Try to keep your list to 3 items or less of each type in each comment so they don't get super huge; just make a new comment if you have more to add.