I checked the "Works of..." titles that had been recently reprinted by Reformed presses to see how many 16th and 17th Century sets you already had. I was impressed. You've already got David Clarkson, George Swinnock, Henry Bullinger, Henry Scougal, John Bradford, John Bunyan, John Calvin, John Dick, John Flavel, John Gill, John Howe, John Knox, John Lightfoot, John Newton, John Owen, Martin Luther, Philip Doddridge, Richard Baxter, Richard Sibbes, Samuel Rutherford, Stephen Charnock, Thomas Boston, Thomas Brooks, Thomas Goodwin, and Thomas Manton.
But you're missing some others, including Ebenezer Erskine, Edward Payson, Edward Reynolds, Henry Smith, James Durham, James Hamilton, Jeremiah Burroughs, John Robinson, John Trapp, John Witherspoon, Ralph Erskine, Robert Baillie, Robert Harris, Robert Trail, Thomas Peck, William Bates, William Bridge, William Perkins, and William Tyndale. Most (but not all) of those have already been brought together as collected works at some point.
You should also try and get the 54 volumes published by The Parker Society in the nineteenth century, and the more recent Courtenay Library of Reformation Classics.