While not that common in the USA, Deutz diesel engines were a good option for the Army Quiet Generator program. My company manufactured them for a military contract.
They were a good engine but it involved a learning curve because air cooled diesel’s were new to us. We had to tweak each engine to meet the generator output requirements.
We built many stationary gen sets for remote operations around the world. We used mainly US diesels but from my experience, Yanmar were some of the most reliable engines.