If you believe HSI will go up, for the strike price of 16800 & expiry date of 29 Apr, 15227 is the best choice among other warrants with same strike price & expiry date.
If you believe HSI will go up, at strike price less than or equal to 16800, I would buy 15964 instead of your pick. The reasons are (1) it has longer expiry; and (2) it is much more under priced than 15227 meaning a greater gain potential.
Good luck.