Of the two -- 75 every time. Bigger footprint means more surface area: more options with scaping; being able to add more fish; etc., etc.. My local LFS often does $1/gal sales so it doesn't have to be the biog box stores where you'll find a deal; and where you are located, you should have a plethora of options to choose from.
How big is a 60g Marineland tank BTW?