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.

DFA World Core Equity Institutional (DREIX Quick QuoteDREIX - Free Report) : 0.27% expense ratio and 0.22% management fee. DREIX is a Global - Equity mutual fund, which invests their assets in large markets, leveraging the global economy. With annual returns of 11.96% over the last five years, this fund is a winner.

JPMorgan Small Cap Value Fund R5 (JSVRX Quick QuoteJSVRX - Free Report) . Expense ratio: 0.84%. Management fee: 0.65%. JSVRX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. This fund has managed to produce a robust 10.56% over the last five years.

Janus Henderson Contrarian A (JCNAX Quick QuoteJCNAX - Free Report) : 0.99% expense ratio and 0.7% management fee. JCNAX 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. With a five-year annual return of 15.84%, this fund is a well-diversified fund with a long track record of success.

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.