Which stock brokerage is the best to use in SG?

Like what Gabriel said, you can try them out to better understand how they work. Another way to go about doing this is to go for the ones that charge less commission!

Every platform has its pros and cons, plus different people like different types of user interface.

I suggest you sign up for a few of them, try out the platform's user interface and see which one suits you.

Signing up is free, you don't need to pay registration fee or deposit any money to start. So just go sign up and try them all.