Changing Metacity's window-placement behavior

For a GNOME user, there are several ways to modify window-placement behavior. These are the ones I’m currently aware of:

1. Patch Metacity to behave differently.
2. Replace Metacity with XFCE’s xfwm.
3. Replace Metacity with Compiz (i.e., activate 3D desktop effects).
4. Replace Metacity with KDE’s kwin.
5. Replace Metacity with Openbox.