Android's biggest issue (OS stability aside) is that HTC make them all (or virtually all?), and HTC have taken their eye off the ball in an attempt to chase crApple.
Winmobile's (pre v7) was that HTC made them all, same applies as above. v7 is not released, not backwards compatible with earlier ones, a bit of an unknown.
Nokia's Symbian has fallen over simply because of lack of foresight. Symbian, even now, is just the backend OS, not the frontend.
crApple falls down on 2 massive flaws - a very poor phone reception (not just latest, which is dire), and its reliant on gayTunes, which is piss poor on Windows.
Gooseberry, or whatever it is that RIM sell is purely for corporates. There is absolutely no reason for a consumer to have one over a proper smartphone.
I know crApple fanboys will always say that gayPhone is best. You will never change their minds. In some cases they are right, eg if you want an gayPod primarily but with a handy phone built in. But in many cases its not the best, particularly if the 'phone' bit is the most important feature.
Windows works well for those that want massive flexibility, but its pre v7 future is over. v7 will lose that flexibility. Very good if you want to sync with Exchange Server collabaration tools.
Rasberry is ideal if you want to manage many phones in a corporate environment and can afford the required BES.
Nokia (Symbian) and Android both lack any particular strengths that stand out, but if they meet your needs, then they are worth considering.