Light mode, default theme. I like the throwback but for the sake of formatting to what everyone else that isn't logged into the site is gonna see, I'd rather make sure I'm seeing what 99% of others are when making articles.
Used to be quite partial to the older tempstyle (not the retro one, but the theme prior to 3.2), just because I hate change. I think I could, for the longest time, keep loading the older UI because it hadn't been deleted yet. I've really come around on this though--Shaun always makes great looking UI.