Do you think investing in ETFs or SSB is better?

Depends on your risk appetite, SSB for low risk and ETFs for medium risk. You can consider investing in both to diversify

To each of its own. Want less risky go for SSB but around 2.5% return/issue. Depending on issue. Only default will be if government defaulted. ETFs will be riskier, following market conditions. There will be dividends(if applicable) and capital gains.

If you are young with no or little responsibility and willing to take some risk, go for 80%ETFs and put like 20% in SSB. If you scared, then put SSB. You can even put 100% in ETF if you dare since its your money. You have to google and do some research to see which suits you.