When choosing an apple for this kohlrabi apple salad, sweet-tart apples like Gala or Braeburn are a good choice. Gala apples have a very well rounded apple taste — they are crispy, juicy, and have a sweet slightly tart flavor. Braeburn has a bold flavor but is not quite as sweet as Gala — overall I think it has a nice blend of sweetness and tartness. I often use these in salads.