Which phone OS is better, and why?

Since all the WP related threads in this forum seem to be full of discussions on this, regardless of the thread's topic, I thought we could use this thread to discuss those things and keep the other threads clean.

So, which OS do you think is superior? What's worse about the others?

EDIT:

I'm surprised at the number of serious and intelligent comments this post is getting, considering that I made this thread as a slightly sarcastic reaction to the annoying "which OS is better" fights in the comment sections of my other posts. It's interesting to see that this thread, which was made specifically for that type of pointless arguing, does not seem to attract any of those fanboys. Edit 2: Seeing how many people take this thread seriously, I'm curious to know how many of the people who write comments on this actually read the entire post. So if you read this, please add a ° at the top of your comment ;)