Large or small does not usually apply to rowsize in this arena, but to the number of rows. Anyway, it all goes to total storage space needed for the table.

1,000,000 rows * 128 rowsize is larger than 100 *1,280.

Another issue is how the data is used. If you are heavy into OLTP (transaction level work) as opposed to OLAP (warehousing and reporting), you will be better off with smaller extents. Oracle tends to retrieve an extent at at time (if the OS buffer permits), so extent size vs system buffers is also a small factor.