Not used any of the new ones, but I'll just leave some thoughts here.
Out of the olds phones, I've only ever used like, friends BB or Iphones, but I have my own S2.
I found BB annoying to use, quite clunky with both software and hardware.
Iphone, too restrictive, not much room for personalisation without going to the trouble of jailbreaking. I would probably HAVE to jailbreak if I owned one just to like using it.
Android, personally I love it. It's just really easy to use and you can have it almost any way you want. I've not even found the need to root my phone yet cause I already love it too much.