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.

Let's take a look at some of our top-ranked mutual funds with the lowest fees.

Goldman Sachs International Tax-Managed Equity Investor (GHTMX Quick QuoteGHTMX - Free Report) has a 0.9% expense ratio and 0.85% management fee. GHTMX is a part of the Non US - Equity fund category, many of which will focus across all cap levels, and will typically allocate their investments between emerging and developed markets. With yearly returns of 12.74% over the last five years, this fund clearly wins.

FPA Queens Road SmCap Value Adv (QRSAX) is a stand out amongst its peers. QRSAX is a Small Cap Value mutual fund option, which typically invest in companies with market caps under $2 billion. With five-year annualized performance of 11.36%, expense ratio of 0.86% and management fee of 0.66%, this diversified fund is an attractive buy with a strong history of performance.

Allspring Spectrum Aggress Grow I (WEAYX): 0.7% expense ratio and 0.25% management fee. WEAYX 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. With a five-year annual return of 11.33%, 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.