Achyuth Kumar is very overrated Kannada actor and not loyal to Kannada film industry. I don't think he is underrated. He is one of the worst actors ever and often overacts.
Even Tulu actors who are lucky to have landed in Kannada Film industry like Rakshit Shetty, Rishab shetty and Raj B Shetty are very bad actors and known for overacting and poor expressions.
Ram kumar is a product of nepotism and not underrated. His father is a producer. He came to the film industry under the influence of his father in law senior actor Rajkumar
Navarasa Nayaka Jaggesh is the most underrated Kannada actor. He is the best Kannada actor till now presently active. No present Kannada actor can come close to him in terms of acting skills.