I would really like to know the margin policy for these brokers. Zerodha is excellent and required only 40% of SPAN margin to take a position. I think this point is important as it allows greater leverage and should be a significant factor for higher volume intraday traders, probably as important as the low brokerage and turnover charges. What is the point of a discount broker where you need to put up higher cash margin?
Tradejini is missing here, it has a model similar to Zerodha, 20 per order
http://tradejini.com/pricing.php