I learned flat 3's and found them much easier on it than on my stairmaster. Yeah I can flatground other boards, even a plankage M3. My point to all that was to say if you want a boards for flatgrounds and butter, everyone I have met has found softer boards MORE fun than others, not that they can only butter soft boards, just that doing the same stuff on softer boards is more fun. Yeah this would be useless if it was just me talking, but this held true for like 8 or 9 people. All of whom had varied boards preferences from stiff and long, to soft and short, camber, and alt-camber.
That thing I do to escape the world and have fun with my friend