On my opinion, the modern style is as in Example 1. Long ago, people were expected to read the whole paper. And in the end of it to see "Thus we proved...".

Nowadays they want to see quickly what is there. Because there are too many papers. So is it very common nowadays to write an introduction with all definitions and precise statement of results, and discussion of their significance, and examples (if they are simple), and then to start proving the things. Many people just will not read after the introduction. Sometimes because they can prove the statements themselves. Sometimes because they are not so much interested.