My first thought is to assume you weren't thinking of performance art. If that counts, it is far and away the art I most detest, even though the performance aspect of it (and lack of a product to actually own) led the artist closer to an ability to earn a living through art than any other style to date. However, it was so lacking in substance it could hardly be called art.
If performance art is to be ignored, well--I am a fan of so many artistic styles that it almost seems a betrayal to say there is art I don't like. If I had to make a statement like this, there are aspects of pop art that do not thrill me. There is a "mass-production" feel to pop art that sometimes makes it seem to lack substance--a common criticism. Among the worst offenders are those who claim, "this is art because I say it is" and frame a blank sheet of paper, etc. The optical-illusion-as-art is not among my favorites, either.
I wanted to answer the question because it is intriguing, but I wish to say I've seen performance art I like, and I am a fan of pop art, as well. There are no complete answers here, and no still I inherently dislike. So, just call me the waffler.
Good question as always, Wayne.