What do you like to do when you are there?
Years ago my answer would have been simple, I would have answer Beach without even thinking about it! Beach means summer and summer means no school and the beach, for a kid, it's always so much fun... The mountains can be fun too but, as a kid, I wasn't very interested into going hiking and I never liked the temperature.
Today I still rather be warm than cold... But I love both of them and it's difficult to make a decision... I think I would choose the mountains today, because I love hiking and taking pictures of wonderful views, and it's calm, while the beach tends to be crowded most of the time and loud...
What about you?