If you had to pick just one then VOO is the way to go. It gives medium diversification with some of the tech weighting which should give good returns in this age of AI. Also the fee is 1/3 that of SPY, the original S&P 500 tracking ETF.

Looking to the future, I think the US global dominance is decreasing over time. We had a good run since WWII but our strength has kept the world safe enough for other countries to develop economically and therefore our economic influence as a percentage of the world total has and will decrease. Therefore VT, Vanguard Total World Stock Index Fund ETF, is looking good.https://investor.vanguard.com/investment-products/etfs/profile/vt

Also outside the US, if you had to pick one country to invest in, you might try India. It has the same population as China but it's a democracy and it has excellent demographics. Many young working people and not many old retired people. Tons of tech professionals there too. (Notice how many CEOs of American tech companies are from India) Here's some India stock ETFs as a starter for research:https://money.usnews.com/funds/etfs/rankings/india-equity

Finally, here's one I think is super reliable and always seems to do well in almost any timeframe you want to look at. It is Warren Buffet's Berkshire Hathaway B. Good to put maybe 5% of your long term investment in, and just let it ride forever!https://finance.yahoo.com/quote/BRK-B?p=BRK-B

Not Investment Advice hahah :D It looks like it is, but it isn't! I'm not anyone's investment advisor. Everyone needs to do their own research. For entertainment only! :)

Oh and BUY VOLTs 🤣