I've had them all. iPhone, BlackBerry (legacy and new), Android, and WindowsPhone.
Currently, I am using my WindowsPhone the most. Cortana (Microsoft's Siri type voice assistant) is amazing. The live tiles on Windowsphone is very nice, but there are much fewer Apps available than on iPhone or Android. I do like Android for the customization available and the huge Apps selection. Lately, the quantity of Apps for Android have rivaled iPhone. Now, for PURE BUSINESS MANAGEMENT nothing beats a BlackBerry. If you are super busy, need COMMUNICATION and text/email management bar none, BlackBerry is the best tool. But there are few Apps and some do not like the physical keyboard. The younger crowd? They are still stuck on iPhone.
They EACH have their pluses and minuses. If you are happy with what you have, then that's the deciding factor.