Best Data Providers for Backtesting

 

Hello,

Can anyone recommend a good data provider for backtesting EA's?

I currently use TickStory (Dukascopy) but the history is limited to only a few years, especially for the indices. For example history for the S&P is only 5 years. The maximum history is for the majors such as EURUSD with 9 years.

I want to backtest a long term trend following system at 99.99% quality over a long term period of say 10-15 years. I preferably want to test on indices and commodities as well as forex.

Does anyone know if this is possible?

What data providers is everyone using for long term testing?

Thanks in advance! 

Reason: