I am commenting based on location itself
Kovan Residences is near to heartland mall and at a area with more activity, very suitable for own stay.
Scala is located among schools, hence there will be demand for for housing from the expat located here due to the international schools.
Its next to circle line. Circle line is a bonus as commuters can expect to get to city with lesser crowding as compared to the other MRT lines.
Greenwich is located at a more secluded place. But its with its own commercial unit. Owners can enjoy the peace and serenity without the hassle of traveling far for their daily needs.
Hope this three answer your questions.
Got any need for my assistance, feel free to give me a call.