F.P.
White would be fine. Putting black stain in the cracks is risky and if not done just right will look a mess. Painting the interiors will help give the cabinets a more uniform look. You can glaze the cracks with a dark glaze, if you have lots of crevices to accent but again, if you are selling the home, why bother. I personally hate painted white cabinets because they do not last in the average household. After 3 years, I found myself tearing my kitchen out and buying new. Good luck