Recently:
Jack Reacher Series by Lee Child
-Off the grid loner who goes around doing whatever he wants which typically means busting bad guys and picking up chicks.
Joe Ledger series by John Mayberry
-A spec ops team leader with multiple personality disorder saves the world from zombies, genetic freaks, super viruses, and vampires with nukes. Not nearly as corny as I made it just sound:
Repairman Jack series by F. Paul Wilson
-Another off the grid loner who takes care of problems the law cannot. Over the course of 16 books he saves the world from an ancient evil.
The culture novels by Ian M. Banks.
- Old school space opera that follows the shenanigans of a post scarcity society as it involves itself in intergalactic politics.
The second book: Player of Games and the 3rd: Use of weapons is some of the best sci-fi writing of all time.
When I finished all of the Jack Reacher novels my search lead me to Joe Ledger and Repairman Jack. I enjoyed both of those series immensely.