It depends on the markets you are trading. One well rounded platform is MultiCharts. It is capable of being used in multiple markets, and it is useful to all levels of trading experience. Here is a link with more information - http://www.forex-trading-unlocked.com/MultiCharts.html
It depends which country you are from. It is best to not go to a deep discount brokers just because their commissions are the lowest.
For example, in US/Canada commissions for interactive brokers are the cheapest but that does not mean that you should actually use interactive brokers. It is just not meant for beginning traders.
In US/Canada commissions will range from 0.99$ per trader to $19.95 per trade.
If you choose some broker with around $5 commission per trade then their platform will be more user friendly then the ones with deep discount brokers.