There is never a wrong time to invest in mutual funds for retirement. So, if you're still looking for the best mutual funds, the Zacks Mutual Fund Rank can be a great guide.

The easiest way to judge a mutual fund's quality over time is by analyzing its performance, diversification, and fees. Using the Zacks Mutual Fund Rank of over 19,000 mutual funds, we've identified three outstanding mutual funds that are ideally suited to help long-term investors pursue and achieve their retirement investing goals.

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

Goldman Sachs Large Cap Growth Insights IR (GLCTX Quick QuoteGLCTX - Free Report) : 0.66% expense ratio and 0.5% management fee. GLCTX 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. GLCTX has achieved five-year annual returns of an astounding 13.77%.

Empower Large Cap Value Inv (MXEQX): 0.96% expense ratio and 0.59% management fee. MXEQX is a part of the Large Cap Value category, and invests in equities with a market capitalization of $10 billion or more, but whose share prices do not reflect their intrinsic value. MXEQX, with annual returns of 11.07% over the last five years, is a well-diversified fund with a long track record of success.

Kopernik Global All-Cap Institutional (KGGIX): 1% expense ratio and 0.9% management fee. KGGIX is a Global - Equity mutual fund investing in bigger markets like the U.S., Europe, and Japan; these kinds of funds aren't limited by geography. With a five-year annual return of 12.76%, this fund is a well-diversified fund with a long track record of success.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.