mp3. Background hissing == bad, it reduces the quality, which is very bad for complex musical styles. Analogue formats also degrade over time and when played and copied. Also, convenience, ease of sharing, can edit things or do your own, can be encoded differently as you like.
Maybe it's what I listen to, but I have never seen anything released exclusively on vinyl

, even seeing ANYTHING that is mentioned as being on it is rare. Then again, a fair bit of my music fairly complex compared to a lot of music out there and low quality detracts from it quite a lot in my opinion.