Working hours will definitely be very long tbh. However, dont give up and be sad on this itself. There will be a lot of exposure that you will gain working as an auditor because you get to work with a lot of clients from different industries. So there is how you gain exposure which you cannot have in commercial. So once in, hold onto it for at least a few years to make the experience a worthy one before deciding to move on to other finance roles.

As to which big 4 to choose, well all of them are really not too bad among each other. It all down to what position and engagement exposure they are providing to you.