Whether VFV or VOO is a better choice for you depends on your preferences, goals, risk tolerance, and investment account type. You should purchase VFV if you want to avoid currency fluctuation risk and want a hassle-free way to gain exposure to the S&P 500. Conversely, you should purchase VOO if you'll be holding the ETF in your RRSP (you'll avoid the 15% withholding tax on dividends) and you have USD readily available or can convert CAD to USD at a rate that makes sense.