CSPX vs SPY

I’m a fresh investor despite many years ago did CPF investing with DBS Vicker.. (under my brother guidance) (he did paid for lessons under those trainer where I later found out in hwz & then here they seem not reliable) example: Pauline, Sean group & then now Adam Khoo. But my brother admire Warren Buffet.

Most here say CSPX is better as in

CSPX : 15% withholding tax, lower expense ratio, have accumulating funds, compounding internally, no estate tax, is etf link to S&P 500 index.

SPY: 30% withholding tax, higher expense ratio, have estate & death tax, is index fund link to S&P 500. (SPY is also etf right?)

My brother reasoning to pick SPY due to it is index fund, have compound interest which is good for holding 20 to 30 years for retirement.

SPY 1 share is more expensive than CSPX right?

My brother want me to invest in SPY & no care about CSPX.

But my finding online suggest CSPX is better to hold for long to act as retirement funds.

Hoping to convince my brother.

And both of this does it have monthly dividend or is depend on how many share you sell in one sums.