Investing decisions can be hard or easy, complex or simple. I vote for easy and simple almost all the time. Simple portfolios, simple but oversimplified does represent a real danger, have been recommended for many decades by some very impressive and renown market wizards. They work!
Here is a Link to one of the most successful portfolios practiced by David Swenson as reported by Adham Sbeih:https://socotracapital.com/guide-investing-retirement-managing-portfolio/
Swenson recommends 6 basic asset classes. His suggested allocation looks like this:
Asset Class Allocation
US Stock Market 30%
REIT (Real Estate Investment Trusts) 20%
Intl Developed 15%
TIPS (Treasury Inflation Protected) 15%
Intermediate Term Treasury 15%
Not the most simple portfolio, but not very complex either. It is an example a solid winning compromise. I love these solutions. Copying this portfolio might not be too bad a long haul asset allocation. The data over several timeframes suggests it’s a winner. It closely follows the 60/40 stock/bond mix.