Answer:
The word that better express eagerness is panting.
Step-by-step explanation:
Even though I answered "panting" in this question and despite the question give me only one answer (Which word), I think that "Still" can be expresses like eagerness and I am going to explain it here. Whether you are in "panting" for something, maybe you are waiting for a specifically situation or thing is going to happen. You are anxious about, for example, to get some money, to get a job, to pass in an exam etc. These happening can be understanding like "EAGERNESS".
Now I am going to talk about the word "Still". Before I start, I need to put here an example about that: I am still waiting your payment about my work. In this example, you are anxious for waiting the payment about a work you did and it refers to "eagerness". In other hand, this word can be used without this meaning, as the follwoing example: I'm still here. I won't help you, though. In this example is not like an eagerness. You are just telling you are not help the other person.
In spite of answering only "Eagerness", I explained about other word that can be express like "eagerness".