Do you mean which puts out a higher amount of firsts and 2:1s? if so you can use unistats to find that out but it doesnt mean anything because it comes down to you as an individual person
Do you mean which has better research? if so that will depend on the area of physics and tbh shouldnt be a factor you consider really because you wont get to do any until your final year project (unless you are lucky enough to get a summer placement there, but not all unis offer this)