I am yet to try NOW from finvasia, but I bet it would be good as it is maintained by NSE itself. I am using BSE BEST which is very stable and at par with NOW. But some users like
@TraderRavi faced problems with BEST.
You won't get good charting with the above mentioned platforms.
Coming to scalpert, it has charting but the platform is so unstable that it becomes untradeable. So better not to consider it for trading.