While I think that the question isn't really the exact cup of tea for this stack exchange, I will try to on the other answer.
Assumption is that the noise in the cafe makes it difficult for you to work because of two factors:
- It has human conversation
- It has random but reasonably loud noises.
Both these factors cause your brain to take notice of the noise rather than concentrating on your work.
With that in mind, the music must not only drown out the noise, but also should not introduce its own level of distraction. This can disqualify not only the music with quiet or changing volume, but also with vocal part that "makes sense".
But it is difficult to suggest a genre of music without knowing your preferences. For example early punk is loud enough and vocal part is difficult to make out, but you can find this very music distracting, but tibetan monk chants can calm your mind enough for you to become sleepy.
So perhaps you want to share something about your general music preferences, and then somebody can provide specific examples of what you want.