In addition to what Michael said, the first sentence is a little off. If you are speaking about a specific time you went to the beach, you would say "I enjoyed the holiday at the beach the most", but if you are talking generally about whether you like the mountains or the beach better, you should say "I enjoy holidays on/at the beach the most", or "I enjoy beach holidays the most", or "I enjoy vacations at the beach the most".
Cheers!