Dynaudio Contour 30 or ATC SCM40

These are very different speakers and more info needed to make any kind of useful recommendation.  What’s the rest of your equipment, what types of music do you listen to and how loud, what speakers do you have now and what kind of improvements are you looking for, and what sound characteristics are most important to you?

Which ever one you like the sound of better. If you can't go to a dealer and listen to them then order them both and send back which ever you don't like.