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.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

PGIM Jennison Value Z (PEIZX): 0.58% expense ratio and 0.44% management fee. PEIZX 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. PEIZX has achieved five-year annual returns of an astounding 13.34%.

GMO Intl Developed Equity Alloc R6 (GAAWX): 0.01% expense ratio and 0% management fee. GAAWX is classified as an Allocation Balanced fund, which seeks to invest in a balance of asset types, like stocks, bonds, and cash, and including precious metals or commodities is not unusual. GAAWX, with annual returns of 15.05% over the last five years, is a well-diversified fund with a long track record of success.

Columbia Seligman Tech/Info Inst3 (CCOYX Quick QuoteCCOYX - Free Report) . Expense ratio: 0.82%. Management fee: 0.81%. Five year annual return: 23.9%. CCOYX is part of the Sector - Tech mutual fund category that invests in technology and lets investors own a stake in a notoriously volatile sector, but with a much more diversified approach.

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.