My top 3 are probably all Tom Clancy books. My favourite has to be:
Without Remorse (Basic plot), *minor spoilers*
Without Remorse is the first book time wise in the Ryan-verse series; a series of books focus on and around a character Jack Ryan. Though he only appears in this book in once short scene, his father does play a large part in the book. The main character however is John Kelly a former US S.E.A.L. who served in Vietnam, who after a tragic accident losses his wife. His life however changes one day when he meets a young lady, Pam. Pam has run away from her life of abuse from drug dealers. He learns to love again; only to find out the horrid past that Pam has went through. John Kelly decides that he must take revenge as the local police are almost turning a blind eye to the drug dealers. At the same time however a high risk operation to save troops from a POW camp in Vietnam is being planned, Kelly is faced with 2 dangerous missions.
Why I like it:
Tom Clancy (the author) covers the topics so well, and in no way does it ever become a James Bond style fantasy type book. Everything is extremely well researched so although the book is fiction it is made very believable. The book shows both sides to every person, and covers dark subjects such as cold-blooded murder, torture and even rape and is a hard hitting, at first it surprised me. The book is never a cliché' and is always following new directions. Trust me, once you start reading it you will become obsessed, and will not put the book down.
The other Ryan-verse Clancy books (that I have read) are all equally as great, with "the hunt for Red October" being another favourite of mine.