I really enjoyed all of the following series at one point. No particular order.
John Sandford's "Prey" series (including the virgil flowers offshoot as well as the Night Crew)
Lee Child's "Reacher" books
Brad Thor's series w/ Scott Harvath
Vince Flynn's series w/ Mitch Rapp
Stephen Hunter series w/ Swagger(s)
( I think these got me back into reading fiction after a very long time away. I ate them up.)
I also liked the "Dragon Tattoo" series.
More recently I thought the first book of the Hunger Games Series was good. the 1st book was fun because it was different and a neat premise. By the 3rd book it got downright horrible though.