I dont like either term as they are both conceptually flawed. Both imply a "negation" or denial of some possible reality. I consider the entire concept of "god" or the supernatural in general to be nothing more than social and cultural constructions, which cannot be tested or investigated in a manner that would satisfy my standards of proof. Thus, in MY reality, there is no god like creature pulling the strings of the universe.
To be "atheist" requires an active negation of the concept of god. However, a concept for which there is no empirical or tangible evidence either in support or against cannot be negated. I am just a human being that has moved beyond a "social meme" that was implanted in my brain by society and parents. To argue that "lack of belief" in a god is equally a social construction, is to confuse cause and effect . To be "agnostic" is to leave open the possibility that the hypothesis of a god can be proven under certain conditions. The problem is, the question itself cannot be tested and is therefore does not even meet the criterion of a "hypothesis" in an empirical sense.
Finally, a theist can argue ad infinitum that there are alternative ways of determining reality beyond basic empirical reasoning and experimentation. However, at the end of the day, all they are left with are unproven claims and evidence that cannot be substantiated independently. For the theist, their subjective "experience" of the supernatural is real and produces tangible "feelings" that are used as evidence to support their personal reality. Thats great, and if it brings them peace, so be it. However, subjective reality does not, and cannot prove any reality outside of one's own experience.