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.

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

Invesco Value Opportunities R (VVORX) has a 1.24% expense ratio and 0.6% management fee. VVORX 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. With yearly returns of 16.74% over the last five years, this fund clearly wins.

Fidelity Advisor Capital Development O (FDETX): 0.53% expense ratio and 0.52% management fee. FDETX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. FDETX, with annual returns of 15.25% over the last five years, is a well-diversified fund with a long track record of success.

Artisan Global Value Institutional (APHGX Quick QuoteAPHGX - Free Report) . Expense ratio: 1.01%. Management fee: 0.98%. Five year annual return: 10.2%. APHGX 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

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.