That's what they say every year...
well big and small is very subjective.
based on what i understand, one problem in photography is under poor lighting conditions, you will have parts of a photo overexposed and parts underexposed. i experienced this enough when traveling, especially outdoors. this makes crappy photos, eg if the background is correctly exposed, i look super dark, but if I am correctly exposed, the background is whitewashed. so like goggle's hdr+, smart hdr simply takes many photes at different exposure and stitch the best bits together. so if you have good lighting, smart hdr isnt going to affect much. but if you have poor lighting, the difference will be much more significant.
lens wise, it supposedly have larger sensor and pixels, which in theory should translate into better low light performance. however, it is ultimately still a small sensor, so you might see improvements, but it wont provide any jump in quality. of course, there are other things that can further improve low light photography (not sure about these in XR or even XS), such as better OIS to allow slower shuttle speed, etc.
i am not too concerned with portrait mode and zoom because most people dont usually shoot portrait modes, and while the 2x zoom which is better than nothing, is not exactly useful since it's only 2x zoom. also, you can only choose 0x or 2x zoom, nothing in between.
like you, the size is a major minus for me, but the above and the A12 chip is why i may choose the XR. the neural engine is about 8-9 times faster. i would expect a lot of developments in the AR, AI, ML area, so it may be worthwhile to futureproof that. But that is me, i will use this new phone for at least another 3 years.
if size is the main deterring factor, at least hold both in your hands before deciding. my gf also said she will never upgrade from her 5S, but she cant stop laughing at my 5S now