Sky Scourge Invincil
Partly whether the shapes are aesthetically pleasing, partly when you did it. A lot of abstract art is just in the right place at the right time, where it's unusual and interesting. I personally think most abstract and modern art are a load of BS and photorealism is the way forward. Just my opinion though.

candy
Personally, I think freedom makes some abstract art better. Not being afraid to do something new with your art. However, you should remember to make sure the piece has the balance that will make it provoke the emotion which you are trying to portray. All masterpieces have meaning and emotion behind them.

Alica Patrick
Abstract art is a form of an art which is mainly based on non realistic portrayals, which are visually precise depictions of substance or scenes. In majority of the abstract art the mood of the art may be emotions of the artist. As emotions can be awfully clear thoughts, abstract art is known to be unknown to something based in usual reality. Much of the work of abstract artists and painters is based on the idea that shape, color and texture have intrinsic rate in their own privileges, and can aggravate a reply still while used to make unidentifiable or non-realistic work. As it is said as emotions of artist change art also changes... may be because of that some abstract art better than other abstract art

Richard_S
With art as with anything that is subjective "Better" does not necessarily mean "worth more". Sarah Thornton's book "seven days in the art world" explains a lot about why certain art and artists become famous, renowned, collectable and valuable. She explains how the "art world" works from the students through to the galleries, dealers and so on. I can really recommend it and I think it will help to answer your question. But just because an artwork is abstract, it doesn't mean that you can't make judgements about it's quality, as is the case for any other type of art. It is just that those judgements will be as much depending on your own response to it as on aspects such as the skill with which it was made, the time taken to make it etc. What makes one piece "better" to you is as much about your response as about intrinsic quality. But whether other people value it in the same way might have something to do with how the work was made, the intention behind it, the degree to which the artist is successful in communicating something to a wide group of influential people, including art teachers, buyers, galleries and dealers. If you love your own work it would not be "worthless" to you, it just might not appeal to those people sufficiently to put monetary value on it.