"Best" is pretty subjective, and thus the metric at work here is my personal opinion. I found Windows 7 to have several problematic UI choices that imply that

"Best" is pretty subjective, and thus the metric at work here is my personal opinion. I found Windows 7 to have several problematic UI choices that imply that it could use some more polish. (another difference between Apple and microsoft, apple ships less features but more polish, and micriosoft the reverse.) I've not found any other phone OS that really compares, with Windows 6.5 being probably the worst ever. (I'm talking smartphones here, of course.)