Well, 'Teenage Mutant Ninja Turtles: City at War' is highly recommended. It has an epic storyline that involves the turtles in a large - scale conflict in their city. It's full of action, drama, and great character development. Also, 'TMNT: Secret History of the Foot Clan' is interesting as it delves deep into the history of one of their main antagonists, the Foot Clan.
One of the best tmnt comics graphic novels is 'Teenage Mutant Ninja Turtles: Tales of the Teenage Mutant Ninja Turtles'. It has a collection of different stories that showcase various aspects of the turtles' lives, their relationships, and their battles. It's a great read for both long - time fans and those new to the tmnt comics world.