IShares Hand Seng Tech ETF - USD OR HKD Counter?

It is not a currency hedged ETF, so thus its currency is merely a matter of convenience. You will be exposed to the currency risk of its underlying assets and not the purchasing currency of the ETF. There should be no tangible difference between the two.

However, IBKR strangely does not allow users to trade USD-denominated HK ETFs, including 9067 and 9169. So does Tiger Brokers, which relies on IBKR for execution and clearance. So unless you switch brokers, your only option is to trade the HKD-denominated version.

HKD is pegged to USD, they tend to move in tandem, so are 3067 and 9067.

I suppose your IBKR account base currency is USD, and it makes more sense to invest in 9067. If you invest in 3067, you either need to do manual FX conversion or end up having negative balance in HKD (which incurs financing charges).