What's the best brokerage for overseas stock market purchases in the US, LSE?

Hi everyone, I’m intending to invest in overseas companies, those listed on NYSE, LSE etc.

Which would be an ideal brokerage for me assuming
1) I intend to DCA into ETFs in each quarter
2) maybe short term trade US counters within 1-2 month one trade.

I can’t decide between IBKR and SCB.

IBKR have 120 comms per year but I don’t think my trade comms will hit 120.
On the other hand SCB has bad FX spreads.

Can someone enlighten me?