W3 Finsbury Park to Northumberland Park. The part between Wood Green and Northumberland Park isn't any good at all - but between Finsbury Park and Wood Green buses climb up through a park to pass Alexandra Palace. From here you can get the most comprehensive view across London and visit the vast and unlucky palace which has burnt down twice. It is home to the worlds first television studios and the huge Willis concert organ in an awe-inspiring hall.  Very frequent.

For timetable see http://www.londonbusroutes.net/times/W03.htm