But regarding the 'top' importance articles I think the selection has it about right. If I had to choose the 20-30 most important philosophy articles? Clearly the subject and its main branches: Philosophy, Epistemology, Ethics, Metaphysics, Logic, Political philosophy, Aesthetics. Also the 'philosophies of' mind, language, mathematics, religion, science. The periods of philosophy Ancient, Medieval, Early modern, contemporary, and an article on the history to thread them together. The 'transcendentals' such as essence, existence, identity, truth, time, and so on. The main 'tendencies' - Realism, Nominalism, Idealism, Scepticism. Major historical figures always difficult, but if forced to choose two or three from each period I would go for Aristotle and Plato; Aquinas, Scotus, Ockham; Locke, Berkeley, Hume; Kant and Hegel; Russell and Wittgenstein.
On the subject of quality, more later, although this snippet from the Aristotle article may amuse you.
Even Plato had difficulties with logic; although he had a reasonable
conception of a deducting system, he could never actually construct one and
relied instead on his dialectic. Consequently, Plato realized that a method for
obtaining conclusions would be most beneficial. He never succeeded in devising
such a method, but his best attempt was published in his book Sophist, where he
introduced his division method.