Rather depends on the layout, revenue-source & busy-ness of the particular airfield. Eg
If the stands are close together push-backs from simultaneous stands may affect each other.
If a/c have to be pushed-back onto a live taxiway they can block others.
If there are more outbounds than inbounds at a particular time you may want to get the outies out first and vice versa.
And of course subject to any particular country's regulations re priorities, generally heavier/faster/more pax tend to get some degree of positive loading as they are our raison d'etre.
Those are just a few things off the top of my head. There are, of course, an endless amount of variables and in the end it's mostly a balance between the "rules" and common sense.
ap