I love Android because I'm not using the "Android default" launcher but am still using my phone's "stock" launcher (Touchwiz). Android is the only OS on the market that gives you enough depth of customization to allow people to find something that works "best" for them. To me, that is a huge feature.
I haven't found an OS or UI that perfectly matches my personal workflow or thought processes. WebOS was the closest, but half of that was the incredible depth of customizations possible. I had around 3 dozen UI tweaks and customizations installed. It was really good by default but it was wonderful after I tweaked it.
I'm intrigued by WP8 but the app restrictions and lack of customization make it a no-go.
I have tried several launchers on different devices. In addition to my Note2, I have a 7" and 10" tablet running various CM builds with an assortment of launchers.
Touchwiz is my favorite. (Gasp!) I occasionally make use of the multi-window functionality, which not many other launchers can support. It's not make-or-break but it is a stand-out feature.
The integrated Touchwiz apps, which are much maligned by Google-only users, are fantastic if you're like me and my wife, who both predate Google and have accounts all over the place. I need my calendar & task widgets to integrate multiple services ala WebOS Synergy. Touchwiz's calendar/task/email apps/widgets trumps Google's apps. (Ironic, given that the WebOS architect, Matias Duarte is now in charge of Android UI)
My Note2 has enough horsepower that unless you've got the latest/greatest right next it, I don't see any lag or stutter in the animations so I don't feel the need for a faster/lighter launcher.
Coming from WebOS, I like gesture-based controls. If I couldn't get WaveLauncher (which is more like a super-widget than a full blown launcher) to give me swipe up/over to swap apps or access frequently used ones I might be willing to live without multi-window and go through the pain of finding email/task/calendar apps that also have acceptable widgets.
Having said that, my wife might have been happier with the Sense launcher, given that she's a heavy facebook user and less wedded to multi-window. Ironically, the "best" launchers for both of us look to be non-stock launchers, neither of which is available outside of specific vendors.
If she didn't need me to do her tech support, I'd get her the new HTC One when our contract comes up but for now she's stuck using the same phone I have so if she breaks her phone (again) I can give her mine and I can either switch to a backup or get something new. (whee!)