Hi! I would say it doesn't matter much, as long as you pick one and stick to it. At your level, there are more important things to focus on than openings, so it pays to learn one and stick to it. Personally I chose Ruy Lopez as white (super successful, it's easy, and I win a lot), and the Sicilian Najdorf as black (less successful, it's hard to play well). Against d4, I play the king's Indian or the Nimzo, but I don't get to practice a lot.