If white, play Ruy Lopez. If black, against e4 (Scheveningen Sicilian) against d4, Nimzo-Indian and against c4, e5. These however are my suggestions. The opening you decide you play may be influenced by many reasons.
What opening should a 1600 fide play (black and white)
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Technically it doesn't matter, as long as you got a good book on your openings. You can also try to study your opponent games and see what they play. Then, you can prepare for the openning.
White=Italian Game, Ruy Lopez, English, or London.
Black=If white plays 1.e4: Sicilian Najdorf, Sicilian Dragon, Sveshnikov, 1.e5, Pirc, Caro Kann. If White plays 1.d4: Nimzo-Indian, Triangle Slav, Queens Gambit Declined, Queens Gambit accepted. If White plays 1.c4= Symmetrical English or Reversed Sicilian.
Pick 1 opening for white and pick 1 for black against 1.e4,1.d4, or 1.c4.