Start with an easy one eh? Favourite song? Even picking your favourite song from one genre would be difficult enough (and it changes daily) but I think this would have to be the one that’s stuck as a favourite for me without ever becoming sick of it.
I could listen to this on repeat all day. Happiness and sadness all rolled up into one polka-dot Glaswegian ball of pastel-pop (and the video is still amazing).
More info: http://www.strawberryswitchblade.net/