Own what you think you should, but more than that look for things that would delight you every day, without depriving from others.
Truth be told: either Erasmus Portrait or Intercessant Jesus in Basel Kunst Museum collection - I love these two artworks, but it should not be to me to own them, because others should get to love them as well as I do.
But I am not an early adapter, which you could be, though with not with Rembrandt or de Goya. And why so, anyhow? There shall be other things to be discovered, surely.