I say Phaser, especially if you’re traditionally a from-scratch-er. I find the visual componentized nature of unity makes me feel very removed from the structure of my code, and I’m a code thinker, not a visual thinker so I need that structure.

well, depends very much what you want to achieve, if you want to focus on the game and create great content you should go for unity…. if you are more of a code guy maybe pick something else. I go with unity because I can focus on the game not loose time with “engine” stuff….

I would agree to both comments above. Although developing with Unity is a bit quicker and you can create some amazing content in record time, it does abstract you away from the actual code piece a little. By this I mean that for the majority of your time in the Unity interface you are going to be stuck looking at the visual side of it. Phaser is a HTML5 game engine which uses javascript so I personally feel that you would enjoy that a little more and be more comfortable using it since you have a strong javascript background.