I have a love/hate relationship with Shakespeare. Well-directed productions of his works are my favorite plays, bar none. But I get very little out of reading the plays myself, and even less out of poorly done productions. I'm a big fan of Pinter, Beckett, Brecht, Ibsen, Miller and O'Neill, for mastering the "wrought"ing of plays - so well structured.
Christopher Durang is probably my favorite comedic playwright, followed closely by Ives. Favorite more contemporary authors include Ruhl, LaBute, McDonagh, Shanley... I'm not a huge fan of absurdity of absurdity's sake, and I also feel that a lot of new playwrights never learned the rules properly before trying to break them, resulting in some out-there-in-a-bad-way new works.