It depends. When I used to day trade stocks, my favorite platform was RealTick. The problem with RealTick is that it has an endless number of bells and whistles, so it takes a long time to learn how to use it and constant attention to avoid making mistakes.
Not every trader responds well to a sophisticated software platform though. There are many active traders that don’t want to have every possible feature in their trading platform (like some of the manual scalpers I have worked with). They prefer a platform with direct execution and just enough bells and whistles to get the job done.
Over the years, I have gravitated towards simpler systems as well – especially now that I have been so involved with the trading of currencies. Working with currencies is a lot simpler than trading stocks, so the platform does not need to be so high-tech (for most people). If you want to get a free, live demo of the simulator I recommend click here. You will be able to practice buying and selling in the live FX market and place simulated trades in the platform. It is super cool and a great learning tool.