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.

Buffalo Large Cap Fund (BUFEX Quick QuoteBUFEX - Free Report) : 0.95% expense ratio and 0.75% management fee. BUFEX is a Large Cap Growth option; these mutual funds purchase stakes in numerous large U.S. companies that are expected to develop and grow at a faster rate than other large-cap stocks. With annual returns of 11.51% over the last five years, this fund is a winner.

JPMorgan US Equity Fund A (JUEAX Quick QuoteJUEAX - Free Report) : 0.94% expense ratio and 0.4% management fee. JUEAX is a Large Cap Blend fund, targeting companies with market caps of over $10 billion. These funds offer investors a stability, and are perfect for people with a "buy and hold" mindset. With yearly returns of 12.05% over the last five years, JUEAX is an effectively diversified fund with a long reputation of solidly positive performance.

Victory Sycamore Established Value R6 (VEVRX Quick QuoteVEVRX - Free Report) . Expense ratio: 0.54%. Management fee: 0.45%. Five year annual return: 10.51%. VEVRX is a Mid Cap Value fund, which usually invests in companies with a stock market valuation between $2 billion and $10 billion.

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.