Can't speak for other mods, but I can for my own. I uploaded a grass and steppe mod last night and just completed a snow and light snow mod tonight. I beleive I have done all the open ground terrains. Didn't do any modding for CMBO or CMBB, so mine are all recent.
I used and liked Capt Wacky's arid terrain grid. I got the idea for the terrain appropriate, subdued grid lines from him. When I didn't find a sand mod (didn't look that hard), I made one myself (I was getting smoked in a desert tank battle, and wanted the help).
Capt Wacky used 20 a meter grid. Blah Blah Blah got me wanting a finer grid. So I made a 10 meter grid mod, which works better for me. Then I had to do a whole set.
There are several others, but I wasn't willing to download something that didn't have a preview picture. Some from previous versions will work with this game. Lastly, if you have a lower-end system, you might look for low-res mods. If you have bandwidth to burn, check them all out.
And Capt Wacky, I apologize for hijacking your thread.