A very short canon of philosophers who are great writers, and may help teach how to make good arguments:

(I have divided this list into “analytical” and “Continental” philosophers (for a detailed discussion of the differences between the two traditions, see my essay on this at http://refusalofsilence.com/what-are-continental-and-analytic-philosophy-35-theses-and-3-provocations/).  Note that in general the mostly English-language philosophers in the “analytical” tradition are quite good at making arguments, and today that alone really defines “analytical philosophy,” a term that originally indicated an approach to philosophical problems through analysis of language).

“Analytical” philosophy: 
-Bertrand Russell
-Ludwig Wittgenstein, Philosophical Investigations (A great work that shows a philosopher thinking out loud).
-Nelson Goodman
-Michael Dummett, Thought and Reality
-Paul Boghossian, Fear of Knowledge
(More to be added; stay tuned).
History of philosophy:
-Aristotle (Great place to start.  His writing is very lucid.  He defines everything and does so very precisely.  He is concise but never pedantic like some English philosophers).  The standard English translation of the complete works is by Jonathan Barnes and is in 2 volumes.
-Plato (His conversations are overly didactic, with Socrates feigning ignorance to lead the person with positive ideas in demonstration of his failure and the truth to which he is then led, but Plato’s Dialogues are the classic model of argumentation through dialogue).  The standard English translation is by Edith Hamilton in one volume.
-Descartes
-Spinoza (Precise definitions; never mind the arguments, though they are also precise).
-Hume
-Locke
-Rousseau

“Continental” philosophy:
-Jean-Paul Sartre (Being and NothingnessSaint GenetThe Family Idiot, essays in the several volumes of Situations).
-Michel Foucault (a model of a certain kind of eloquence).
-Jacques Derrida (a model of a rigor and eloquence a different kind, focused on French-style close analyses of language; literary scholarship in English has emphasized this since the 1930s when discussing literary texts; Derrida does this with every concept he takes up, and also with his own sentences, and he does to exhaustion; some find this exhilarating, others annoying, and you cannot normally do very much of this in English prose academic writing, even in English literature departments, but it is one style of philosophical writing and clarity, though it is never simple but always complex.  The French language facilitates this, and it is possible to do in English, but should be done very sparingly).
-Jacques Rancière, Disagreement
-Alain Badiou, Being and Event.  (Very dense, like Sartre, but if you stay focused it is also very lucid and clear).
-Giorgio Agamben
-Friedrich Nietzsche (the only great literary stylist in German philosophy; he writes incisive prose and likes the one-liners known as aphorisms).
-Walter Benjamin
-Hannah Arendt
-Franz Kafka (a writer, not a philosopher, but, his incredible ironic voice aside, he is a great prose stylist, including in translation.  Very clear and straightforward, useful literarily when he wants to be ironic).