Is there a better index fund to own then?
There are funds that are more diversified than funds tracking S&P (e.g. $VOO tracks S&P 500). $VTI should represent the total US market. $VWRL should represent the total worldwide market.
Not sure about “better to own” though - that depends on your risk profile. Of course both of them underperformed S&P 500 in the recent history.