I working on a research paper in Machine Learning, the paper is regarding a classification problem of which I have achieved 98% accuracy. However some other paper working on the same dataset claims to have achieved 100% accuracy. Is it still possible to use my results as state of the art results and publish my paper or should I just search for another dataset? If yes then do I mention the previous results paper which got 100% accuracy as previous work, or should I just disregard it?
Since you are aware of the other work you should report it. But you should probably also try to verify its claims.
Whether your own work is worth publishing or not depends on some things. To be valuable, it needs to advance the state of the art on some dimension and accuracy is only one. If you can achieve "really good" results in half the effort/time/cost, you probably have something worthwhile. It might make the difference between something that is feasible or something that is not.
But it would be a serious breach to ignore the other work.