If I were upgrading, here's why I would prefer the 5.5" iPhone 8 Plus over the iPhone X.
Screen real estate is a major factor for me. The 5.8" X screen is the exact same width as the 4.7" models. That diagonal measurement is steep. The X screen is simply a little taller than the 7 screen. The aspect ratio is different. Photos and videos made on the 7 and 7 Plus will be cropped on the X in full edge to edge. You can tap the screen twice, and it will show the images in full, but they won't be full edge to edge. I prefer the 5.5" screen that's wider in its aspect ratio. I have too many custom wallpapers I would have to edit to fit the X. My existing photos and videos would not show in full edge to edge on the X.
Don't get me wrong, the iPhone X is a very nice formidable smartphone. But I'm not sure I'd like the tall skinny screen. I'll wait until next year and see what is offered then.
Price is another factor. There's nothing I see with the X that justifies paying $200 more. Others may defer, and that's a personal decision.
Here's the difference between the 4.7" models and the X screens. The gray area is the 4.7", and the blue shows the additional area of the 5.8" X.
Screenshot courtesy: Apple Inc.
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