Which site provides the best 1 min intraday charts for NSE?

Preferably with buy and sell call signals.

If you are asking for a website, you can check out TradersCockpit

Google finance also does a good job, if you choose OHLC(settings->Chart type->OHLC you will get 2 min, 3min, 5 min charts. It is near real time. It is not 1min as you asked. But just one more source were you can visualize the charts.

It is possible that you can download one min data table from Google Finance for last 15 days.
Later plot it on excel to have a look at the chart!
Just fyip.