MCHI, PGJ or 3169 for china exposure?

MCHI and PGJ are both US-domiciled ETFs. Your dividends will be taxed at a rate of 30%, as compared to 10% for 3169.

As for VWRA and EIMI, you have to consider what is the purpose of investing into each of these funds. If your intention is to get greater exposure to China, then you should directly invest into a China ETF, but if you want to ensure diversification in your portfolio, sticking to VWRA would be a better option. Do note that EIMI only covers emerging markets.

EIMI. I probably wouldnt want to get sole China exposure into their companies due to lack of transparency and political issues. Can consider HK as a gateway to China but with more security and transparency. But recently there has been a lot of political turmoil too, so be warned.