Well, I don't think you should try to like a genre, it should just come naturally to you. So, I would suggest exploring bands that are a bit heavier than what you listen to, but whose vocals aren't as guttural or harsh as those used in death metal. I'm sure if you find interest in bands who are heavier, it may spark your desire to seek more aggressive, heavier music. I'm not sure what bands you are into though...
The whole work, in general. Though I admit lyrical themes and album art are of a far lesser importance to me than the music itself (i.e. competence, arrangement and significance).