Should I buy a US stock using a local broker or an American broker?

I am a Singaporean and currently a trader in hedge funds. I often provide my investment philosophy in my personal blog, some of my investment philosophy is US stocks.

This is a frequently asked question from my readers:
Buying US stocks through US brokers is cheaper? Or should we buy it through a local (Singapore) broker?

There are several questions before making a decision. Concern is not just commission.

If you are dealing with a local broker, it is likely that they have an account with an American broker. So when you trade, you trade directly to a US broker. Of course, local brokers are not free to do so, so they will charge an intermediary fee. You pay your transaction on T + 3.

If you trade with a US broker, you automatically stop the middleman fee, so you end up paying a lower commission. But you must deposit your money into your US brokerage account prior to the transaction, and you will pay on the T-day. You can not often transfer funds to the United States to Singapore, because it will incur a lot of wiring fees.