If it has to be an artist, and a dead artist, I am happy to go with Hogarth. For a start he had a clear voice and a message to speak. Secondly, his morality resonates today when bling, greed and ambition are still the ruin of young men. Thirdly, he's classless - unlike some sycophantic knight of a court painter. Anyone today from any background can identify the types limned in Hogarth's savage caricatures. And finally, the NG's portrait (left) is timeless and would engrave well.
Sorry, no polemic on those noisome crooks of banksters - £50bn in fines and not one yet jailed. It's too much to satirise.