I have been struggling with these types of questions in my career as well. For a while, I was more of a front-end developer doing Swing rich-client desktop app

I have been struggling with these types of questions in my career as well. For a while, I was more of a front-end developer doing Swing rich-client desktop applications and touched on some mobile development with some basic back-end. The last few years, I spent doing more of the back-end development, "big data" technology like Hadoop/HBase and worrying more about HA, consistency, redundancy. What I found is that if your not careful with the type of job, this applies to everything but more so for back-end, you can be stuck doing grunt work, data quality, operations and system up keep. Moreover, I think most of the innovative, creative, and interesting work is moving away from back-end and into the space of data scientist type positions. So currently I am stuck in between, I have experience in front and back end -- this makes it hard to find the right job. I think I might go back to doing mobile development just because it seems to be more of a greenfields with some hard problems still to be solved. In terms of pay it's about the same, maybe back-end developer gets 10% more. That's just my thoughts.