I was on the fence between #4 and #5 but I ended up teetering to #5.
That was mostly because #4 confused me. I think it's trying to communicate this sense of vibrancy through the colors (of which are beautiful), but that effect gets lost by the instagram-looking filter and the incongruency of the font color, which should have been a lot bolder. I think the theme also feels like an afterthought, because aside from the castle, there are few things that really try to make yellow as the main focus.
I think the render for #5 was a bit oversharpened, but I like how it addressed the theme without being literal. Maybe a border could have given it more punch.