I use GXC...FXI is only 25 Chinese companies listed in HK. GXC has more exposure to small caps with 100 holdings. Both FXI and GXC's top holdings are the same.
CAF is directly investing in A shares, so it is a more direct way to gain exposure to China. If Chinese market does a sharp reversal, CAF will go up the most. CAF is not an ETF though, and volume is much smaller.
That said, I don't think Chinese market is a good representation of the Chinese economy. It is filled with state owned big banks...my impressions are state owned big companies are inefficient...