There are no real "bad" seats to avoid in this section. There are no large obstructions with any of the seats and there is a good view of the entire field. The only potential problem with this section is the possible inability to see the action in the left field corner but that is an issue that almost all seats on the third base side of the field face.

View from Section 519 at Citi Field
This is the view of the field from Section 519 at Citi Field.