Get the Eckers translation if you want an accurate mirror of the Middle English. I have an older translation in "modern English prose" that is very readable and enjoyable, by R.M. Lumiansky. Or, just for fun, Geraldine McCaughean's adaptation for young readers (she manages to finesse the "Miller's Tale" neatly, but her "Death's Murderers" stands all on its own merits) illustrated superbly by one of my favorite British illustrators, Victor Ambrus. Ambrus's portrait of Chaucer is alone worth the price of admission, but his knights are knightly, his honest yeoman are stout and true, his ladies are lovely (although occasionally silly) and his Pardoner is absolutely slimey. Great artist.