I started using free platforms but the quality was often not that good. After testing several things out, I'm using a platform called https://openart.ai/ where you can actually chose among the most popular models. There I often use Kling 1.6 or 2.1, VEO 2 or Pixverse 4.5. These are the model that I loke most and I use them according to the task at hand and how much it costs. They are not free to use but the difference is so big that for the moment, I stick with these ones. I believe that within some months we will see free platforms available for video generation.