I've been considering these two options (VOO and VT, or even something like CSPX and VWRA, which are Ireland-domiciled, to take advantage of the tax benefits since I'm from Latin America) for my long-term retirement portfolio. Personally, having diversification outside the US through a global index gives me more peace of mind, although on the other hand, if the US economy is affected, other economies also tend to be affected. On the other hand, the SP500 has historically had slightly higher returns.
In addition to that, I plan to have 10% of my portfolio in gold and 5% in Bitcoin.
If you had to choose a single index to invest in over a 20-year period, either an ETF like VOO for the SP500 or VT for the global market, which would you personally prefer and why?