For me, control over what I work on or how I solve a problem is the key to satisfaction. The more rigid the constraints, the less creativity allowed, the more boring the job. It's hard to find jobs that consistently allow enough creative latitude to keep the tasks fun and interesting. The OP's point about not being a general software engineer (implying specialization) might make sense. I imagine that more specialized you are, the fewer the people that are around that know more about your area than you. So you might get more creative leeway because you're the expert.