Home Depot HD has outperformed the market over the past 20 years by 3.89% on an annualized basis producing an average annual return of 12.41%. Currently, Home Depot has a market capitalization of $405.32 billion.

Costco ( COST 0.85%) and Home Depot ( HD -0.78%) carry market caps of $389 billion and $406 billion, respectively. Consequently, I'm sure many investors are also customers of these two massive businesses. Both retail stocks have rewarded shareholders over the past few decades, but one is obviously the better company to buy right now.

Costco (NASDAQ: COST) has been a big winner so far this year. Consumer staples stocks have generally had a good year, with the Consumer Staples Select Sector SPDR Fund (NYSEARCA: XLP) providing a total return of 15%.