The first smartphone I picked from my text phone the LG EnV2, was the HTC 8X.
First and foremost, the in my opinion, cleanest and easiest on the eyes interface. One look and I seen what I needed to see. Android and iPhones are too busy and have many navigation levels for various things, even with organization from what I observed.
The swipe to the all encompassing list of apps has it in alphabetical order and is searchable (like a certain start menu somewhere else...)
Gmail, Facebook, Phone contacts all meshed together nicely without any third party or additional effort other inputing in login credentials and authorizing the device with the service.
With the default map app, and Internet Explorer, it was at basic and internet communication connectivity and information reference ready to go out of the box.
Document viewing was adequate. But, the default PDF reader won't let you access the documents that is supposedly downloaded in the local phone folders and there is not an on board file navigator to your personal files of any type, but the Office integration, especially with OneNote, I find to be good.
Internet Explorer is limited to 6 tabs, and the history of past webpages is not tied to each tab, but as a part of the overall "back" button history. So one has to be careful in navigating. That maybe a bit awkward for some out there.
Native Remote Desktop without additional client software on the PC end is another big reason why I went with the Windows Phone. Though, I had to use a third party ConnectMe app. I did not want to have to deal with something like Splashtop ever again.
Skydrive syncing and integration is very nice (though syncing from the phone can take a bit of a while depending). I have never made use of Dropbox, but I don't think I would need it after having Skydrive.
Still, at this point, I am not that tied to a phone ecosystem. I can be persuaded for an Android Phone if it offered seamless, no additional work with Remote Desktop running, Office, and obviously it can Gmail integrate. All on a just as an eye pleasing interface with pertinent information forefront. I do not need customized backgrounds and customized icons - I am not looking at the phone menu for long anyways.
It would be nice though, if my next phone still tied well with my PC and Tablet PC.
Also, I do not need an "Official" Youtube app. Internet Explorer on the phone is more than adequate. For viewing and commenting that is. Uploading is another story.