Finally, if you're not sure whether Commonwealth Bank is the best bank to buy, but you're wanting exposure to the banking sector, then the VanEck Vectors Australian Banks ETF could be a great option. This exchange traded fund gives investors exposure to Commonwealth Bank and the rest of the big four banks through just a single investment. It also provides investors with access to the regional banks and investment bank Macquarie Group Ltd ( ASX: MQG ). I estimate that its units currently provide a forward dividend yield in the region of 5%.