On my new contract i had the D900 after having the W810i and it took me 3 days to send it back. The D900 IMO is a terrible phone.
It is so unuser friendly and makes everything a chore. You can assign your own text message alerts, it takes at least 7 key presses to start a new text, and the list goes on.
I now have a K800i and it is the best phone i have ever had. It is even better than the old winner the W801i. The K800i has a better screen than the W810i and for me its a better size, and the O/S is a bit quicker.
Simply put, the K800i does everything you want .... easily.
You wanna text, then its one flick of the stick.
you wan to set diferent ringtones for different people ... no problem.
you want to surf the internet ... no problem via Opera.
You want to take good photos, you can (says 3MP, but i think its a bit less, but still excellent)
You want shortcuts to different programs on your phone, easy.
If i were you, get the K800i, it is a really good phone and the best in the list you have supplied.