What are the differences between VFIAx and VFINX and which one would be a better investment option for me?

The main difference between VFIAx and VFINX is that VFIAx is an institutional share class of the Vanguard 500 Index Fund, while VFINX is the investor share class of the same fund. VFIAx typically has lower expenses and a higher minimum investment requirement compared to VFINX.

If you have a larger investment amount and can meet the minimum requirement, VFIAx may be a better option due to its lower expenses. However, if you have a smaller investment amount, VFINX may be more suitable for you. It's important to consider your investment goals, risk tolerance, and financial situation before making a decision.