Investing in mutual funds for retirement is never too late. And the Zacks Mutual Fund Rank can be an excellent tool for investors looking to invest in the best funds.

The easiest, most reliable way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. The Zacks Mutual Fund Rank, which covers over 19,000 mutual funds, has helped us identify three outstanding options that are perfect for any long-term investors' portfolios that is retirement-focused.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Nuveen Multi-Cap Value I (NQVRX): 0.82% expense ratio and 0.69% management fee. NQVRX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With annual returns of 13.9% over the last five years, this fund is a winner.

Franklin Utilities Advisor (FRUAX) is a stand out amongst its peers. Sector - Utilities funds like FRUAX focus their investments on firms that provide essential daily services to millions of people like electric power, gas distribution, and water supply. With five-year annualized performance of 9.17%, expense ratio of 0.56% and management fee of 0.46%, this diversified fund is an attractive buy with a strong history of performance.

Fidelity Growth Company K (FGCKX Quick QuoteFGCKX - Free Report) is an attractive large-cap allocation. FGCKX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. FGCKX has an expense ratio of 0.66%, management fee of 0.62%, and annual returns of 15.69% over the past five years.

We hope that your investment advisor (if you use one) has you invested in one or all of the top-ranked mutual funds we've reviewed. But if that isn't the case, it might be time to have a conversation or reconsider this vitally important relationship.