If you are looking for safe long-term income dividends are a better choice than a savings account as they should generally grow with inflation.
Dividends can be cut and generally will go down during a recession. But they tend to be far less volatile than stock valuations.
https://www.indexologyblog.com/2016/09/12/dividend-volatility-and-correlations/ Dividends are slightly less than half as volatile as stock valuations. The rate for a savings account or money market can also go down. You can buy a CD to lock in an interest rate for a fixed period.
As others have pointed out, for long term investments Stocks are the better choice. After owning a stock for a year you will also have "qualified dividends" meaning you pay taxes at the lower capital gains tax rate vs. interest which is always at the income tax rate.
If you are looking for the most favorable tax treatment consider an ETF instead of a mutual fund for investments held outside of retirement accounts.
https://www.fidelity.com/learning-center/investment-products/etf/etfs-tax-efficiencyFor investments within a retirement account consider FZROX. It is total market fund from Fidelity with 0 fees. Fidelity won the race to the bottom and is hoping you will stick around and buy funds with fees too. VTSAX and FZROX are both total market funds and as a result will pay slightly less dividends than an S&P 500 fund due to the smaller stocks in a total market mutual fund.
I tend to go with stocks for everything even the emergency fund. While we still work almost all rare emergencies can be handled by cash flow before the credit card is due. If we occassionally need to pull from stocks on average we will come out ahead.
The only time I would recommend cash/savings account is if you have a known near term expense.