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 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.

MFS Blended Research Core Equity R3 (MUETX Quick QuoteMUETX - Free Report) : 0.74% expense ratio and 0.4% management fee. MUETX is part of the Large Cap Blend section, and these mutual funds most often invest in firms with a market capitalization of $10 billion or more. By investing in bigger companies, these funds offer more stability, and are often well-suited for investors with a "buy and hold" mindset. With annual returns of 10.24% over the last five years, this fund is a winner.

VALIC Company I Mid Cap Strategic Growth (VMSGX Quick QuoteVMSGX - Free Report) is a stand out amongst its peers. VMSGX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations. With five-year annualized performance of 9.35%, expense ratio of 0.77% and management fee of 0.64%, this diversified fund is an attractive buy with a strong history of performance.

Invesco Small Cap Value Y (VSMIX Quick QuoteVSMIX - Free Report) . Expense ratio: 0.84%. Management fee: 0.64%. Five year annual return: 12.27%. VSMIX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion.

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.