If it's for investment, most likely i will go for sub sales if the unit condition is still good. It's all depends on age of the building, maintenance, and of course accessibility of the area/building. If the new project worth it, why not?
But i believe that new project RM1000psf might come with small size compared to subsales with RM600psf right? Most of the new project i would say considered over valued and their size is so small. No matter for investment or own stay, I will still consider the size, layout, accessibility. Depends on what you want. First, make up your mind of what you really want perhaps?^^