Essays of GK Chesterton, Hazlitt, Emerson, Robert Louis Stevenson, Santayana, Bertrand Russell, HL Mencken, Oscar Wilde, William James
Almost everything they wrote, but some good starting points:
Chesterton - Heretics, Varied Types
Hazlitt - The Plain Speaker, Table-Talk
Emerson - Essays: First and Second Series
Stevenson - Virginibus Puerisque, Across the Plains
Santayana - Little Essays ed. Logan Pearsall Smith
Russell - Unpopular Essays, Sceptical Essays
Mencken - Selected Prejudices
Wilde - Intentions
James - Talks to Students, Memories and Studies