I have read the entire series in just the last 6 months (Kindle Rocks!!), and I have not found other books/series that has the right combination of good writing, a strong hero that is smarter, stronger, quicker than the bad guys. Earl and Bob Swagger (Stephen Hunter) comes close, so does Joe Pike and Elvis Cole (Robert Crais) and possibly Jason Bourne. The problem is Swagger is getting old (age), Pike and Cole encounter bad guys that don't receive pay-back till the very end, and Bourne is slowly becoming less interestring under Lustbater. I love Child's opening scenes and his crisp detaild writing, and I love these quick read action books that are better than any current movie release. Any reccomendations from Reacher fans...????
I remembered seeing this for Vanished by Joseph Finder.
"If Jack Reacher met Nick Heller in a dark alley, my money's on Reacher. But it would be ugly. Or would it? Actually, I think they'd go for a beer together and set the world to rights - because Joseph Finder has given me a terrific new hero to root for. This is an action-packed, full-throttle, buy-it-today-read-it-tonight series that you definitely shouldn't miss." -Lee Child, author of the Jack Reacher novels
I love the Reqacher series and the others you mention. I have found Daniel Silva to be marvelous as well as Ignatious, Lehane, Gross, Parker(RIP) as the best of the dialogue mavens. I'll have a book out in a few weeks, Cooch, that follows in these lanes. Robert Cook, author of Cooch
If you don't mind some dated material, the great John D. MacDonald's character, Travis McGee, is a similarly strong, smart, quick, tough character. He is also independent, living in the Florida Keys on a houseboat he won in a poker game, taking "salvage" jobs when he needs the money. He's not quite as physically over-sized as Reacher, but he is big and tough and very skilled at self-defense. He makes up for any size difference with his womanizing, and the chauvinism of a bygone era. If you like the character, there is a wealth of material! I don't know how many Travis McGee novels there are, but there are plenty.
Just got started on Randy Wayne White novels---his character, Doc Ford, in the earlier books, is a retired (though 30ish) undercover operative, not CIA or FBI, but some extremely violent and deep cover type of government agency, now living in an old fish shack on Sanibel Island and running a biological supply business. Slowly he gets sucked back into wet work, and loves and loses lots of interesting women. Not Reacher, but then, who is? You might like Doc, though; his lifestyle and sidekicks are pretty cool and the author's descriptions of fast boats planing over dark waters under midnight skies are excellent. Try to start at the beginning, with Sanibel Flats---the first chapter reels you right in.
I just read Cooch (by Robert Cook) mentioned above. I think it might fit well with what you are looking for - a very intelligent hero, lots of action and believable scenarios. I appears to be the beginning of a series (at least I hope it is!) and develops several interesting characters.
A series I really like before I got in the Reacher novels, was by Stephen Hunter. The main character is Bob Lee Swagger, different than Reacher, but they "are cut from the same cloth". It is a long series, that goes thru the 3 generations of Swaggers. Point of Impact is the 1st book in the series, "The Shooter" was based on it.
Just read my first Mitch Rapp thriller, and it was pretty good---I'll read more in the series, but he's no Reacher. Mitch has waaayyy too much backup. The fascinating thing about Reacher is that he does so much on his own, and even when he does have some backup, it's kind of iffy, it seems.
Ditto on the suggestions for Vince Flynn, Daniel Silva, Brad Thor, Michael Connelly and John Sandford. LOVE them all. Flynn, Silva & Thor are more politcal/spy and Connelly and Sandford are more cop/crime novels. If I had to pick only one, it would be Connelly though. The first book "Black Echo" is a slow start, but the series just gets better and better. All have a main character that continues through a large well established collection of novels, so you can read a lot without waiting a year for a new book. I recently finished the Alex Kava "Maggie O'Dell" series and enjoyed that. I also recommend the as the Tess Gerritson "Rizzoli and Isles" series -BUT avoid the TV series because it is really bad.
I have to warn folks that as much as a love Lee Child, he is a bit of a jacket quote sl*t. He is also on Harlan Corbin's books promoting her as a sidekick for Jack Reacher. I'm still gonna check out Joseph Finder though!