Best delay I have ever personally experienced is 4.5 hours start of taxy to wheels up in New York. JFK seems to have several hours of taxy if you are lucky most times weather is present.
In Australia, some of the best used to be Sydney before 34R was available for departures. In the busy part of the morning, only 34L was available to take off on, and 40 minutes would have been pretty normal often back then. Then again, an east coast low, howling easterly and 07 for arrivals and departures only over the easter weekend many years back was also chaos. If my memory serves me right, it took nearly 2 hours from closing doors to airborne one night.