My choice was mostly based on personal interactions with you two and how you are solving problems as mods. But as both of you are doing a good job i therefore choosed the guy who worked for longer 
Don't get me wrong, I'm not questioning your decision. Mitchell is an excellent choice. Interestingly, no staff member has voted yet.The thing with mprep is that i dont see him often. He is probaly more of the working behind the scene guy.
Well, I think it truly comes down to where you're looking. I've heard a lot of differentiating stories from people, regarding who they think (based on what they saw) are the most active ones.