Custom UIs, Good or Just Memory-Wasting?

Lately in the world of Android we have been hearing all about custom UIs, overlays, skins, or whatever you want to call them. If you aren't familiar, the most popular UIs added to Smartphones running Android are HTC's Sense UI, Motorola's MotoBlur, or Sony Ericsson's Timescape UI. On one-hand, UIs usually make Android better in a way, like polish, widgets, or animations that make the UI look more modern and user-friendly than stock Android. On the other hand, custom UI's tend to lower benchmark scores, make updates take much longer than expected, and slow down the phone. One example is the Droid Incredible to the Nexus One, the Incredible runs Sense UI and the Nexus One runs stock. All of the well-known benchmarks (Neocore, Quadrant Standrard, Linpack) are higher on the Nexus One than on the Droid Incredible. It all really is personal preference: do you want a phone that runs stock Android with less features but immediate updates (Droid, Nexus One, G2), or do you want a phone with more features, better experience, a bevy of widgets, but a slower phone (Droid Incredible, Droid X & 2, Xperia X10)? Now onto the big debate, which UI is the best? In my opinion, Sense UI is the most beautiful UI I have ever seen on Android. It includes around 50 jaw dropping widgets, Scenes, and better-designed menus and adds a huge amount of polish to Android OS. Motoblur is probably the roughest around the edges of the three, but has a bunch of Motorola widgets that you can resize depending on what you want. Motorola also added a bunch of Verizon bloatware on the Droid series phones running this UI. Last but not least, Sony Ericsson's Timescape UI adds a bunch of animations and changed menus, as it is hard to actually tell this is running Android. It is true that custom UIs do slow down Android updates as the X10 and all of its relatives are stuck on Android 1.6, and Samsung's Galaxy S series is still on Android 2.1 (UI called Touchwiz 3.0). So, do you like customs UIs or think they slow down Android too much? Be sure to tell me in the comments! Also, follow and LIKE me by using the buttons on the right. Happy New Year!