Bulk-Insert Select performance over individual Inserts
If we're talking performance, first approach is better. Here is why:

Whenever new data is inserted into a table, the indexes will also be updated, and physically reordered. In the case on InnoDB, not only are the index files updated, but the data file itself could be reordered, it is clustered based on the primary key. So, re-ordering/updating is an expensive operation, and you want to minimize it.

When you do bulk insert, the indexes are updated at when the statement is finished. i.e. after inserting all rows.
On the other hand, when you do individual inserting, physical files are updated after each insert.

The overhead of the last select statement in the first approach is negligible.