"Good" is subjective, technically proficient is objective.

Technically proficient can be objectively analyzed - utilizing music theory or a synthesizer in a way that could not be achieved by a novice, an understanding of the proper use of EQ and compression, or possessing the ability to play an instrument or sing well. We can compare scientific details, like a lack of unwanted phasing or noise, a higher perceived degree of loudness without a loss in clarity or dynamics, or a "clean" mix with no undesired masking of frequencies. All you need is another song that has a better metric in the category you're looking for.

Good is entirely based on your taste and your perception. Whether your mixdown is cleanly divided like a well crafted prackage or blending together like the ingredients in a cake to end up warm and delicious; whether your sounds are heavily distorted or pure and clean; whether that melody should be quantized to the grid or left a little sloppy. These are questions you'll have to ask yourself, and this is where you need to start looking into yourself and looking into your past. What do your inspirations sound like? What sort of music did you listen to as a child, and how did that sound? What were the sounds of the city or town you lived in? What were the sounds of your school? Of your friends, or family?

All in all, the goal is to remember that you do not exist inside of a vacuum, and that other people are your reference point.