IQfeed for CME/CBOT Emini SIFs
Stable, fast and cheap. Every tick provided not snapshots. A lot of free index stats provided such as Tick, Trin, Tiki, 52 wk his and los, advancers/decliners etc. Very occasional temporary data bunching in very fast markets, e.g. after a Fed interest rate decision, but 99% of the time a flawless delivery. No bad data as yet. Superior to Interactive Brokers feed which I used to use. Customer service excellent. Recommended.