I've tried MIUI. My Droid doesn't like it much. CyanogenMod 6 has been best.
And DF, you are right. I do enjoy having the root capabilities. There are a lot of reasons I may stay with an Android-based handset. I will definitely probably be ditching Motorola and heading to an HTC device, though. You're also right that iOS is nothing special. I kind of realized that after my last post after playing with my iPad and thinking of some of the things I miss about Android. (NOTIFICATION BAR!!!!!!) I'm just saying, the stability and battery life are both key areas that Android seems to be lacking right now. Stability has gotten a lot better in Froyo, but I still have some trouble. Of course, I'm overclocked and rooted.
The cell phone world is definitely not as cut-and-dry as the desktop world for me. Mac OS X is clearly the better OS over Windows. (Notice I said FOR ME, not saying for everyone..) iOS is not a clear winner over Android.