I believe they have changed category1 to include the first several rows in the center section of level 2.
The CM I spoke to when booking my seats said the upper rows of level1 or level 2 in the center are the best seats. Pretty much any of the seats are good, but I would try to avoid the far left or far right. When booking, pull up the seating chart to check where your seats are to make sure they are satisfactory. If not, see what else is available.
Book as soon as possible, because seats are first come first serve according to when you book.