Which brokerage account has the lowest fees?

For local, can use CIMB. If you fund your trading account upfront, the commission is $10 + SGX clearing fees, plus it has a very good screening tool to find companies to invest in.

For overseas companies, I would recommend using one of the overseas brokerages so that you do not have to pay quarterly custodian fees to local brokerages. Interactive Brokers is one of the top recommendations as they have the most attractive commissions. However, the desktop and the mobile device user interface is a bit more difficult to use, compared to say, TD Ameritrade's Think or Swim platform.

Other factors to consider are the ease of depositing and withdrawing money for overseas brokerages. Nowadays with remittances fee almost no-existant, this is not much of an issue (we used to have to pay these remittance fee and it could amount to quite a bit if you transfer regularly e.g. weekly/monthly). Plus most of these overseas brokerages have a local office here in Singapore so you can simply transfer to their local Singapore bank account. Withdrawing money is almost the same, straight to your bank account. For Saxo capital, I heard that you can even fund your account using a credit card!​​​

Interactive Brokers is the lowest fee brokerage, probably in the world :D

Charles Schwab and robinhood if you are able to apply.

These have no fees for many stocks and exchange traded funds

Which are the top brokerages with the lowest fees?

Interactive brokers. https://www.interactivebrokers.com/en/index.php...

What are some other factors I should be considering when choosing to open a brokerage account?

Reputation, dividend fees and forex rates when transferring money to change to the stock currency. Many brokers earn a killing by changing ur SGD to USD.