Honestly I have yet to call an overall winner between my two phones, but below are my personal observations. For whatever its worth, I still prefer my DSLR for regular shooting, but do find these phones are great tools at times.
Portrait Mode = ⅔ Pixel
The Pixel can handle a wider array of items than the iPhone overall, however when the iPhone nails the shot, it is really no dispute IMO. Where the iPhone struggles is with translucent, or narrow items. When it does get the shot correct, the out of focus effect appears to be much more realistic to what a wide open lens will do.
To be honest, I like the iPhone's shot of the leaves a bit better as it is doing a little more of what an Actual wide aperture lens would do. Focus would fall off quite quick on my sigma 1.4 when shooting this same scene wide open. The Pixel keeps most of the leaves in true focus, which isn't true to life. Where the iPhone continues to struggle is with narrow or translucent objects near your focal point as seen with the bars in the top portrait shot. Neither compare to a true wide aperture picture as taken on Film, mirrorless or a DSLR though.
Video = iPhone Xs Max
The auto exposure on the new phone does far better than the 2017 X did at adjusting from dark to light. The phone also has less jittery video when OIS is needed, or when panning. Stereo audio recording also puts this phone in an entirely different league. I am ashamed it took Apple this long to record stereo audio considering they have had dual Mics since the iPhone 4! No excuse for any phone to lack it for the past 5 years IMO.
Zoomed images
Anytime you need to go to 2X zoom I feel the iPhone is superior since it does this optically, as opposed to cropping. Don't get me wrong, the pixel's shots still look amazing at face value, it's when you crop in or do larger prints that it sheds light on this issue.

100% crop (Click for larger)

100% crop (Click for larger)

100% crop (Click for larger)

100% crop (Click for larger)
In both cases the 100% crops look more like paintings than true images, however you can see more of a Picasso effect in the Pixel 2.
Undecided
Low light photos, areas with vast lighting differences, meaning low light, bright light in the same scene. Pixel is sometimes too dark, and the iPhone sometimes brings up shadows far too much.
Storage = Pixel 2
Unlimited full resolution photo cloud storage.. No contest here. Come on Apple, you are the richest company in the world, why aren't you matching this?!?
We are talking about cameras though and the Pixel is still less expensive than the iPhone and there haven't been any issues besides the first batch of Pixel 2 (Non XL) with LCD issues which was LG's fault, just like the screens on Macs having the exact same issues.
Let us be real now. The Pixel 2 is / was, far from a perfect device.
Personally I am on my 2nd device as I had a hardware fault that would cause the phone to crash / power down when running graphics intensive tasks. IIRC there was other user or two here on MacRumors with a similar issue.
And then there was this
Camera problem with many phones
Than an update that caused
annoying buzzing and hot phones.
What about l
agging / slow phones.
And an
Audio recording issue, which for some of us (including myself) results in a now much less useful mic (everything sounds muted).
So no, the Pixel wasn't without problems, and the XL screens were not the only phones with this problem.