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.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term investors' portfolios.

Here are the funds that have achieved the Zacks Mutual Fund Rank #1 (Strong Buy) and have low fees.

Alger Growth & Income Fund A (ALBAX Quick QuoteALBAX - Free Report) : 0.93% expense ratio and 0.5% management fee. ALBAX 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 13.15% over the last five years, this fund is a winner.

LSV Global Value Investor (LVAGX): 1.15% expense ratio and 0.75% management fee. LVAGX is a Global - Equity mutual fund. These funds invest in large markets like the U.S., Europe, and Japan, and operate with very few geographical limitations With yearly returns of 11.01% over the last five years, LVAGX is an effectively diversified fund with a long reputation of solidly positive performance.

Brandes Intl Small Cap Equity R6 (BISRX): 1% expense ratio and 0.95% management fee. BISRX is a Non US - Equity option, focusing their investments acoss emerging and developed markets, and can often extend across cap levels too. With a five-year annual return of 19.24%, this fund is a well-diversified fund with a long track record of success.

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.