Hands down I would say Etrade. I have been with them for 15 years and they are flawless. One flat fee of $9.99 to buy and sell and not a penny more in commissions. You can buy 10 shares or 10 million and just pay the $9.99 in and on the sell side. They also allow trading of Penny stocks that are on the DTC Chill list which many other trading sites do not allow. IMO, Etrade is top notch.
News 
Market Data 
Discover 
AI
