Knockout punch is best if you can get your hands on one.
I used a 3/4" hole saw - $10. This is required for the arbor on a knockout.
A knockout is a hydraulic piece of equipment used mainly
by electricians to punch out holes in electrical cabinets.
(
Greenlee is a very good fabricator of this)
I was able to borrow one from work with large punch/dies for 80mm and 120mm fans.
Makes a super clean cut and is so very quick.
If you have a hardware rental store near you...