Finding texture generators is really hard on the internet, although it is useful to have texture generators out there as well. I don't mean to self promo but I made a video with a planet texture I thought was cool.
I created it using a Blender planet generator from Gumroad. I'll find it later if I can since I have a (way too long) list of planet texture generators in my Google Docs files. Here's the Docs file: https://docs.google.com/document/d/1jstGqrESD3ir-TowbgMbNYni89-A_B4oIycCLezJilA/edit?usp=sharing
Oh wait I found it. Here it is: https://verdestudios.gumroad.com/l/sRaZL