There are some complexities around taxation that you might want to look into on the NYSE listed version, and of course it will be in USD so you will also be playing the FOREX markets while owning the ETF
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Not sure what the tax situation with LSE listed stocks will look like after the Brexit debacle plays out, but personally I’m not willing to take the risk. Also important if you go the LSE route to consider the currency risk again.
I buy an iShares S&P500 ETF on the Amsterdam exchange that is in Euro and accumulates (dividends are reinvested rather than being sent to you). The ISIN is IE00B3ZW0K18 if interested.