Delhi the capital of India has the best transportation in the form of metro. Metro has its connectivity throughout Delhi and in Delhi NCR as well. Its the best way to travel across Delhi. I am a frequent traveller to Delhi and find this best way to travel there.
The airport line is also too convenient for travelling and its very comfortable also. But you should be aware while travelling towards Rajiv Chowk. Its very crowded specially on the peak time. As it is a junction where different routes meet.
All in all, metro has saved delhi from traffic and has given a single platform for everybody to travel.