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.

Elfun Trusts (ELFNX Quick QuoteELFNX - Free Report) : 0.18% expense ratio and 0.14% management fee. ELFNX 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. With annual returns of 14.57% over the last five years, this fund is a winner.

Fidelity Select Semiconductors (FSELX Quick QuoteFSELX - Free Report) : 0.68% expense ratio and 0.53% management fee. FSELX is a Sector - Tech mutual fund, allowing investors to own a stake in a notoriously volatile sector with a much more diversified approach. With yearly returns of 29.84% over the last five years, FSELX is an effectively diversified fund with a long reputation of solidly positive performance.

Ivy Large Cap Growth Y (WLGYX Quick QuoteWLGYX - Free Report) . Expense ratio: 0.95%. Management fee: 0.61%. Five year annual return: 15.82%. WLGYX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers.

These examples highlight the fact that there are some astonishingly good mutual funds out there. If your advisor has you in the good ones, bravo! If not, you may need to have a talk.