Med/surg patients are my favorite: especially when the patient trusts me, has reasonable expectations, is fully committed to participating in their recovery, wants to learn, and has a strong sense of purpose.
Emergency room patients, got to be on your toes with a broad knowledge base-you never know what is coming in!
Behavior Health especially addiction!
Geriatric! The wealth of knowledge and things you learn from them is amazing! They also appreciate what you do