The only advice you should absolutely heed is do not apply to Trinity for Maths. Otherwise, it’s up to you. Do you want an inperson interview? Do you like a big, international college? Could you go for an all-female one? Do you want something central? Do you care about architecture, or food prices? Does endowment matter to you (it sounds shallow, but this can affect rent and how much money the college will give you — richer colleges can offer better grants!)