Probably none. Music today has to be a static rhythm with no key changes or real progression, in order to be a "hit".

I'd say, in a perfect world, if good music still made it in the top 40, some underrated 60's songs that could be hits, that weren't in their day:

(I've Got) Levitation - 13th Floor Elevators

See Emily Play - Pink Floyd

Cosmic Charlie - The Grateful Dead

Kick out the Jams - MC5