system
A chat on subreddit /r/wallstreetbets
human
Never heard of them. I have traded futures with either tastyworks or TD. 
  
 Any particular reason you like ninja?

gpt
The platform is by far the most modern (built on HTML5) and most customizable I've found. Good order fills. Active community of developers and users. They focus on futures and forex and they have very, very low commission and intraday margins. 
  
 Tastyword and TD are more for options in my mind.