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.

Fidelity Select Health Care Services (FSHCX Quick QuoteFSHCX - Free Report) : 0.71% expense ratio and 0.52% management fee. FSHCX is part of the Sector - Health category, offering investors a focus on the healthcare industry, one of the largest sectors in the American economy. With annual returns of 14.36% over the last five years, this fund is a winner.

MFS Mass Investors Growth Stock R2 (MIRGX Quick QuoteMIRGX - Free Report) is a stand out amongst its peers. MIRGX 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. With five-year annualized performance of 13.08%, expense ratio of 0.96% and management fee of 0.33%, this diversified fund is an attractive buy with a strong history of performance.

Neuberger Berman Guardian Adviser (NBGUX Quick QuoteNBGUX - Free Report) . Expense ratio: 1.17%. Management fee: 0.88%. Five year annual return: 11.65%. NBGUX is a Large Cap Value fund. These funds invest in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value.

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.