Which brokerage is best in terms of trading fees for lump sum into lump sum into IVV quarterly for long term say 30 to 40 years?

Actually instead of IVV, why not CSPX or another Irish-Domiciled S&P500 ETF. Irish-Domiciled ETFs are only subject to 15% withholding tax on dividends as compared to 30% on US ones (like IVV).

If you still choose to stick to the US one, you can try Tiger Brokers or TD Ameritrade. Both have low comms and decent FX rates. Main downside for TD is the long approval time, but it makes it up with close to spot FX rates and zero comms.

If you wish to invest in the Irish domiciled variants, you can try Standard Chartered or Interactive Brokers. Do note that Standard Chartered does have a much high commission than the other brokers mentioned here. On the other hand, IBKR does charge inactivity fees.

As such, you'll have to evaluate at the end of the day which option would be most cost effective for you. You can find out more about each of these costs in my detailed article here!