[XPERIA X1 General] msalmank:
The way i see it... it totally depends on what attracts you more - a no-keyboard slim black iPhone like mobile or a professional looking and metallic keyboard bearing mobile. That alone should determine your choice... but considering you want to go into depth:

1. Xperia has more RAM. Infact almost 100 MB more. Which is simply awesome, especially if you are looking to port heavy games onto the mobile or run tons of software. How much RAM will panels take up is a big question, but keep in mind that if needed you could release the RAM taken up by Panels by disabling them or setting them however you want. (Loading 9 heavy panels will probably take more RAM than keeping 9 basic or default panels)

2. When it comes to Screen, though both have the same resolution, Touch HD gives you a bigger display with its 3.8 inch screen over the 3 inch Xperia screen.

3. In regard to camera, the Touch HD is again ahead of Xperia with a 5 MP camera over the 3.2 MP camera in Xperia. However, if one thing Sony Ericsson knows best, it is its Camera... so i can pretty much say that Xperia's 3.2 MP camera would be enough to take on the Touch HD 5 MP camera. Video recording is in both, and most likely Touch HD will match the recording capabilties in terms of resolution with Xperia - but again Camera quality of Sony is expected to be better. Both devices have Touch Focus as well... but one other thing to note is that Touch HD has no camera flash!

4. Main interface - Touch Flo 3d is superb looking. But Xperia Panels are not behind. Though Touch Flo 3D is shiny and extremely attractive, it lacks big time in customization. With Panels, customization is the key... and with time as developers start releasing new panels, we will probably see some really awesome stuff in terms of functionaity as well looks. Not to mention, the way you switch panel mode (fan, side-by-side, etc.) is nothing short. So if you are one who loves to have the possibility of as much customization as possible, like me, then Xperia wins here. And in my opinion, in terms of functionality and extendibility Xperia again wins here.

5. Battery - Xperia carries a bigger battery than Touch HD. Though how much time each will provide, we can't say for sure at this point...

6. Manufacturer - HTC vs. SE. This is SE's first WinMo device, so concerns arise... but given the fact that HTC was behind in this device's manufacturing as well, i say that we can rely on the device.

7. 3G Reception - Foo, a senior member here at XDA Developers has brought to my attention that Touch Pro suffers from poor 3G reception but another member says that this is not the case and that he doesn't face any such problems on his Pro. Considering that HTC has improved Touch HD in various aspects over the pro - bigger screen, higher resolution, better sensitivity to the touch screen, more powerful camera and so on - we will just have to wait and see if the 3G reception in Touch HD is better than Pro or not. As for Xperia, we'll have to wait and confirm for that when it releases.

8. Accelerometer - The major feature missing from Xperia is the Accelerometer. But other than putting a lid on some possibly cool games, i don't have much concern over this. But of course, here the Xperia is beaten by the Touch HD!

Other than that, basic differences are there... LED indicators on the Xperia, and In Call Recording in Touch HD, but none too major to consider here. (i leaved keyboard out of this as i already put that forward in the first question i asked at the start of this post).

Conclusion: From where I sit, Xperia is a winner with its sexy look (c'mon. it. is. steel!), fully customizable interface (panels), more RAM, Flash on the camera, full stylish qwerty keyboard, and more.

Hope this helps... ;)

And if anyone feels like it, then add to the list anything you want.

Best Regards.

Salman Khalid.