I'm pretty sure that the "BMO US equity" fund is an actively managed fund, which is why it has a much higher MER.
To make a fair comparison you should probably be looking at the "BMO US equity index" fund, which has an MER of 0.85% (in comparison to TD's US index MER of 0.53%)
For the low cost option you could also compare the following:
BMO US Equity Index ETF (MER 0.23% + trading costs)
TD US Equity index e-Series (MER 0.33%)
To make a fair comparison you should probably be looking at the "BMO US equity index" fund, which has an MER of 0.85% (in comparison to TD's US index MER of 0.53%)
For the low cost option you could also compare the following:
BMO US Equity Index ETF (MER 0.23% + trading costs)
TD US Equity index e-Series (MER 0.33%)