The Executioner books that were actually written by Don Pendleton are great. It's when he left the series and they started using ghost writers that the quality suffered. Another great modern pulp series that suffered the same fate is The Destroyer. When Richard Sapir and Warren Murphy started the series, it was all about philosophy, political commentary, social satire, and of course plenty of violence. The later books usually try to emulate the formula but the writers usually only succeed with the violence part. Still, each series has a few good books by ghost writers and more than a few great books by the original writers. If you can get your hands on early Executioner and Destroyer, you won't be disappointed.