my initial reasoning was that, i related to the pages' (jake, tavros, horuss) more obvious, surface level traits, and also related to the light players' (rose, vriska, aranea) deeper motivations, problems, and less-obvious traits. so... i'm a page of light!
i've always figured aspect = what you're most driven towards, and class = how you go about trying to achieve that thing. light is knowledge and fortune, and pages are often lacking in their aspect, yet desperately crave it and/or want to give the impression that they're better at it than they actually are. i think that fits me well enough.
i am 100% sure in my aspect being light, but i have considered other classes for myself :P