The only cheat that really affects the gameplay that I use is toggle_fow:
I think it's pretty ridiculous to have characters (and more important: to recruit these characters!) travel all over the map just to know how the other factions are doing...especially since your given all this diplomatic information just like that...

And this is an exception to my "usual behavior", I usually only use cheats that are fun to see, In example: give_trait_feck#