Funnily enough, iirc Foucault viewed a large part of his work as extending the style of investigation Neitzsche initiated in Genealogy of Morals.

I think Nietzsche is great. His prose is a breath of fresh air and he's arguably the greatest literary stylist among philosophers since the Greeks. Sartre was pretty good too, likely thanks to his ability as a novelist. Some later continental philosophers would have really benefited from reading his aphorism that good writers write to be understood.