Okay.
So here is my personal comparison between XZP and U11

Design:
Ignoring the same design with previous xperia or much more elegant aluminum body of previous htc, i find both are equally great in design perspective, in their own way. XZP gives impression of elegance with its materials n shape.
U11 has a bit outdated shape, but feels the best in hand and pocket due to its curve back. Also IMHO the colour is really nice.
Display:
XZP has very rich and vibrant colour, but i still feel sony should set the default at 2k reso. Once your eyes used to 2k display, u can still see the the pixels or lack or sharpness fhd provides.
The 4K capability is nice, but personally I wont watch 4K video as frequent as I watch FHD or even 2K content.
htc u11 superLCD display has more natural colours and due to its 2k native display, it looks sharper at all time.
Sound:
Both has dual speaker, but u11 is definitely better in terms of quality and loudness. I wont comment on earphone because using different earphone is a bit unfair.
Rear Camera:
Outdoors with good lighting, both are equivalently good. However in low light, XZP is way better.
For video, both are good but htc lacks advanced option in this mode.
Front camera:
I'm not a selfie type but i think u11 front camera tends to over expose at all time. The quality is better than XZP though.
Performance:
Both are fast. No hiccups. But htc u11 doesnt keep background apps as good as XZP does.
UI:
Im a blinkfeed fan - easier for me to read all my reading materials from various sources at one place.
Also, sorry to say but for me there's nothing special about sony's ui.
Battery:
Not fair to compare because I have different sets of apps running on both phones. But both phones can easily last u from morning till night.
So which one do i choose? Seriously both are really good. For me, XZP is the clear winner in camera part. It's weird because htc u11 is touted as highest scoring mobile phone camera by DxOMark. But the low light quality and over expose front camera is a let down. But other than the camera, U11 is my pick