The w800i is basically the equivalent to the k750i.
Id get the k800i.
But if i were to choose a new walkman phone, id get the 
w880i
So, If you want it for music, Get a w800i or a w880i. If you want it for pictures, get the k800i.
There is a list of SE phones 
Here. You can click on what you want, IE click Music, Camera etc.