Hi. I use both VUSA and IUSA. Both are good. But I also invest in US stocks directly. You should think about your tax situation - will the dividends be coming to an ISA or to a taxable account?
See my post about dividends
If VUSA pays 1.51% and the fee is 0.07%, this means the raw dividend yield of the S&P 500 is (1.51+.07)/.85=1.86%. This explains why the dividend yield of SPY is 1.9% - because no 15% US withholding tax is taken off. But since we can’t invest in that VUSA is a good option.