I'm currently playing through Castlevania: Order of Ecclesia. It's not the best portable Metroidvania, but it's still really good.
What's cool about the portable Metroidvanias is after you play through all 6 (Circle of the Moon, Harmony of Dissonance, Aria of Sorrow, Dawn of Sorrow, Portrait of Ruin, Order of Ecclesia) you can go back to the first one and it feels like you haven't played it in forever.