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.

Let's break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

Brown Advisory Sustainable Growth Investor (BIAWX Quick QuoteBIAWX - Free Report) has a 0.78% expense ratio and 0.53% management fee. BIAWX is a part of the Large Cap Growth mutual fund category, which invest in many large U.S. companies that are expected to grow much faster compared to other large-cap stocks. With yearly returns of 11.88% over the last five years, this fund clearly wins.

Victory Sycamore Established Value I (VEVIX Quick QuoteVEVIX - Free Report) . Expense ratio: 0.58%. Management fee: 0.45%. VEVIX is a Mid Cap Value mutual funds that aims to target medium-sized companies that possess strong value and income opportunities for investors. This fund has managed to produce a robust 10.02% over the last five years.

T. Rowe Price Health Sciences I (THISX Quick QuoteTHISX - Free Report) : 0.67% expense ratio and 0.63% management fee. THISX is part of the Sector - Health category, offering investors a focus on the healthcare industry, one of the largest sectors in the American economy. The fund is mainly invested in equities, has a long reputation of salutary performance, and has yearly returns of 11.21% over the last five years.

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.