I’d go with 2011 personally. Even though his 2015 season was probably even more impressive statistically, I feel like Djokovic’s 2011 run was the pinnacle of tennis. Novak dominated the year with only 2 losses until September, although his competition was prime Nadal, prime Murray and near-prime Federer amongst others. Djokovic even dominated Nadal on clay which was completely unheard of at the time. Best individual season I’ve ever seen since I started watching tennis about 18 years ago.
Honestly, tennis is boring with Djokovic. You know whos gonna win before the tornament begins.