Cabo San Lucas or Cancun for summer trip?

I would really like to go on a trip this summer to somewhere tropical, and Mexico seems very inciting. I have narrowed my choices down to either Cabo or Cancun. I am 19 and would go with my girlfriend and 2 of our close friends. We would love to go to a place with good beaches, good shopping, good food, good nightlife, snorkeling etc. If anyone could give me insight on if they prefer cabo or cancun and why? Anything helps. Thanks!