It might be how you are preparing the rice. As for the type of rice, I'm quite a novice when it comes to product brand-names, I just go to my local Korean market and buy some rice that looks familiar to me and says "sushi rice" on it.
You should use a rice cooker, or a rice-steamer though if you want to get consistent cooking results. Right now, I'm using a rice-steamer, which is not the best, I prefer a rice cooker which has a warmer... It's a great investment if you eat a lot of rice.