Making a GUI po?p up when Player gets close but which is the best way to go on about it

I am making a sh0p script where if you get close enough to a part it shows a UI

BUT MY QUESTION IS

Which is the most efficient, and the best way to go on about it

--USE A TOUCHED EVENT --USE A MAGNITUDE -- USE REGION3

But what I dont like about magnitude and region3 was that you had to use a while true do loop

while touched event you dont need to use