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, 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.

AQR Global Equity Fund R6

(AQGRX Quick QuoteAQGRX - Free Report) : 0.7% expense ratio and 0.6% management fee. AQGRX 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 annual returns of 11.59% over the last five years, this fund is a winner.

Federated MDT Mid Cap Growth A

(FGSAX Quick QuoteFGSAX - Free Report) is a stand out amongst its peers. FGSAX is a Mid Cap Growth mutual fund. These funds aim to target companies with a market capitalization between $2 billion and $10 billion that are also expected to exhibit more extensive growth opportunities for investors than their peers. With five-year annualized performance of 11.96%, expense ratio of 1.14% and management fee of 0.75%, this diversified fund is an attractive buy with a strong history of performance.

JPMorgan US Equity I

(JUESX Quick QuoteJUESX - Free Report) . Expense ratio: 0.69%. Management fee: 0.4%. Five year annual return: 16.71%. JUESX 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.

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.