You are really the only person who can answer this, but let me offer some guidance: Creative people are most energized when they have autonomy, mastery and pur

You are really the only person who can answer this, but let me offer some guidance: Creative people are most energized when they have autonomy, mastery and purpose. It seems you already have autonomy, because you can select what you are spending your time on. It seems like you already have purpose, because you can see the long term value in skills enhancement. The last part is mastery. You gain mastery by pushing at the limits of your abilities through deliberate practice, so which one of the two makes you feel the best when you're working on it? Select the one where you get the most done, and not the one that appeals to your ego or intellectual vanity, be very honest with yourself, and hopefully the answer will surface. Putting my two cents in, I would say do the deep learning stuff, because there's lots more engineers out there who can put models into production whereas having deep knowledge of deep learning is probably more valuable. But I'm a Deep Learning developer, so I might be biased!