What to hold in non-registered to save cash

I know I am going to owe additional taxes next year due to a side business (no installments yet those should start next year) so I plan to save a certain amount to put me just over what I estimate owing. My TFSA is maxed out so I can not put it in there so I have to use either a HISA or a non-registered account. My best options are either WS at 2.25%, CASH.TO or HSAV in my non-registered account. Due to being taxes I'd rather be conservative with it and not end up with it going down and owe more than is left.

For context, I will be in the 53.53% marginal bracket in Ontario and owe in the ballpark of $75k so limiting taxes on this would be a huge plus.

What is my best option and why?