I've been thinking more about series in the genre that are a little bit more unique and these are a few that I have enjoyed.
Mark Dawson has a series about John Milton, a former English SAS operator who is fighting alcoholism and basically roams and helps people who are in trouble, like Reacher or the Equalizer type stories. A lot of focus on AA and fighting his inner demons. I've read the first 13 out of around 20 novels. You can find them on Kindle in groups of 3 or 4 packaged together and most are on the unlimited program if you use that, so you can read as many as you want for the subscription cost. (First novel is The Cleaner)
Stephen England has his Shadow Warriors series which begins with Pandora's Grave, as well as a prequel trilogy called Lion of God Episodes 1-3. It's been a while since I read them but these stood out a bit due to the antagonist, an Iranian terrorist who is believed to be the second coming of a Islamic prophet that will trigger the battle at Armageddon. The prequel series is about a group if Israeli operators.
John Gilstrap has his Jonathan Grave series which is excellent. His protagonists are former operators who now are basically hostage rescuers. First book is called No Mercy.
Rafael Amadeus Hines (what a name!) has a new series about a character named John Bishop who is an operator but has ties to drug cartel and walks the line/crosses it but it does have some of the same revenge trope you mentioned originally. Only two books so far but they definitely have a different style of prose and structure that I found interesting. First book is called Bishop's War.
I just began a new series by Brian Andrews and Jeffrey Wilson called the Shepherds series. I'm about halfway through the first book called Dark Intercept. It is about a retired Seal operator who is trying to rescue a childhood friend's kidnapped daughter. The thing that makes it different is there is a spiritual/supernatural element to it. Prayer warriors and demon controlled antagonists. It's like a Stephen King story (think Firestarter or Carrie) crossed with a military thriller. It's interesting so far. These authors have another more traditional series called the Tier One series that I have read which is also good.
I'm guessing you're already familiar with the big boys in the genre who are all excellent. Flynn, Thor, Greaney, Cameron so won't list those but those are always first day purchases for me. Same with Daniel Silva's series about Gabriel Allon, Israeli Mossad although his books are all starting to be repetitive in their structure and plot lines. The first dozen or so books were excellent but I'm a little weary of them now.
Anyway, hope some of those are helpful.
