I'm aware of plenty of cases of former Wehrmacht generals and Nazi officers denying personal knowledge of or involvement in the Holocaust. "I was only following orders," "I thought they were being deported," "It was all the SS, not the Wehrmacht," and so on. But were there any prominent Nazis (i.e., those who would've known about the scope and goal of the Holocaust or were implicated in its execution) who outright denied that there was an organized plan to mass murder Jews and other ethnic groups, or claimed that the Allies were vastly inflating the death tolls?
One strong argument against Holocaust denial is that virtually no one put on trial for Holocaust perpetration actually denied the Holocaust. Instead, they would use justifications as you suggested; either they denied personal involvement, they had to follow orders, etc.
However, there was at least one prominent Nazi who later became known for Holocaust denial: Léon Degrelle, a Belgian (Walloon) far-right politician and Waffen-SS recruiter. After World War II, he fled to Spain and became a prominent neo-Nazi activist; indeed, Degrelle is still revered by neo-Nazis today. He argued that there was no gas chambers at Auschwitz and was convicted in Spain for Holocaust denial in a case that was influential in Spanish constitutional law.
There is also the phenomenon of historical negationism to cleanse the image of certain organizations such as the Waffen-SS or Wehrmacht ("clean Wehrmacht"), which can shade into outright Holocaust denial. For example, the postwar HIAG association was associated with denial of certain Nazi crimes such as the Malmedy massacre. However, the magnitude of the Holocaust is such that denying it completely is hard to maintain with any level of credibility, as David Irving discovered.
For the non-denial by Holocaust perpetrators, see:
Douglas, Lawrence (2011). "From Trying the Perpetrator to Trying the Denier and Back Again". In Hennebel, Ludovic; Hochmann, Thomas (eds.). Genocide Denials and the Law. Oxford University Press. ISBN 978-0-19-987639-6.
For more on the Degrelle Holocaust denial case:
Barromi, Joel (1995). "A Matter of Honour – Plaintiffs Locus Standi Recognized by Spain's Constitutional Tribunal". Israel Yearbook on Human Rights. Brill Publishers. 25: 151–68.
Trías Sagnier, Jorge (2017). "La negación del holocausto: El caso de Violeta Friedman contra León Degrelle". Revista de Derecho, Empresa y Sociedad (REDS) (in Spanish). University of La Rioja (10): 48–55.
For HIAG see:
Parker, Danny S. (2014). Hitler's Warrior: The Life and Wars of SS Colonel Jochen Peiper. Boston: Da Capo Press. ISBN 978-0-306-82154-7.