not-so-newguy
I'm the Straw Man in your argument
I tried a few other free ones, but Wix was extremely simple. Nearly all of the setup was click-based and required finding the right template then editing it.
As an aside, I had to purchase some foam for my recent projects and was duly impressed by how expensive a 4' x 8' sheet of two-inch foam is! I know you get a lot of terrain out of that foam, but I still had a bit of sticker shock. I knew that construction materials had jumped in price a lot due to the pandemic, but still...
In another too little too late suggestion category - I base all of my foam projects on floor tiles. I use really cheap linoleum 12" x 12" self-adhesive tiles. I then glue (to the self-adhesive side) a layer of cheap black felt to the bottom. I have not had any problems with warping when I am painting (knock on foam). The tile is also a little lighter than then mdf, which can also warp in my experience.