mycolors can be used without having to install windowblinds, iconpackager etc etc as it comes with the files needed. Plus there are other mycolors themes that can be purchased.

Object desktop is a suite of programs that include windowblinds, iconpackager and others. this choice will give you more freedom over customizing your computer as you can use the individual programs to just change what you want and as there are thousands of free skins, icon packs in the wincustomize galleries it may be better for you.

It all depends on how in depth you want to go. I recommend object desktop just for the value but it comes down to choice. You may find my colors easier to deal with and there are other themes that you can get but you do have to pay for them. (there are only so many free themes)

If you want to change the windows theme you need windowblinds, to change all the icons you use iconpackager, to use widgets you want desktopx.

theme manager in a way is like mycolors BUT in order for it to apply themes you have to have the corrosponding software installed (something you dont need with mycolors) and there are hundred of free suite to download at wincustomize.