If you're willing to compile it, Aseprite is a great option as well.
check my website for the latest tips - always updating with new content!
Matt Parkin did another nice tutorial, talking about the production and the use of floor materials.
So this a very useful Substance Designer 6 guide, explaining how to make full procedural high-quality floor tiles in an understandable manner.
Matt has been running Polygon Piligrimage for quite some time. He published a lot of very cool tutorials on a variety of topics, covering Unreal Engine 4, Substance Designer and other important tools. If you want to learn more about it, go to the official website!