Actually, I have just the opposite opinion, I find that heat transfers last longer than screen printing....if it is done properly. Like anything I suppose, if it isn't done right then it will not last. However, to answer your question, one isn't really better than the other necessarily but instead there is a time when one is more appropriate that the other. For full color, low volume then it's heat transfers...for minimal colors with high volume then it's screen printing. There are many other factors too but those are the main considerations.