For me, Schopenhauer, Bentham, Hume and Singer, hands down, all because of their clear consistent views on ethics, and their rational and / or empiricism.   There are of course others I like very much (Nitchsze stands out) , but the ones above are my favorites.   I really don't like Descartes.  He's clearly more intelligent than I am, this is obvious from his pensées, but I can't see how he could…