[Vivo X90 Pro Plus] extremecarver:
I had to upgrade as my X90PP got crunched into tiny pieces. I went for S24Ultra. So as a quick comparison.

+++ X90PP

Main Camera in very dark places (not that the photos at that darkness serve more than instagram at best). Zoom camera in very dark places.

+

Main camera in dark places a tiny bit better. Same for 3.8x zoom.

Dual wifi reception. Handy when debugging IOT devices. So can have one wifi for data, the other wifi to the IOT device. Samsung lacks this in software (as both use the same Fastconnect 7800 wifi/bluetooth/UWB chip). Dual Network dual Data both phones lack.

Draw:

Mobile phone reception except for Band n75 which so far however my provider uses only for data only tarifs. For phone+data they don't allow it to be used. S24U shows much less bars - but effectively the speed is about the same. At my home I have very borderline 5G and the speed I can get with 0bars on S24U is the same that I could get before with X90PP and 2bars (bars are no real indication anyhow). But yeah I don't really get how Samsung does the bars so that could be improved. On the other hand things like VoLTE/VoWifi or VoNR are much more likely supported by S24U because mobile phone providers push them for it or sometimes have whitelists. On my provider both worked so it was fine. However I think VoNR isn't supported on X90PP but my phone network will only allow for it starting next month. Not sure if 5G Advanced will be supported by S24U. In theory it should be capable while X90PP clearly cannot. But so far the only provider (China Mobile) that has it only lists Oppo Find X7 Ultra as capable.

Size of phone. Both phones are a bit too big for me. In the pocket it's a draw. I would prefer a bit smaller and instead thicker so it fits a big battery. The square design of the S24U destroys the advantage over the cameras sticking out on the X90PP once inside your pocket. I like S24U is wider and a tad less high however it's every so slightly heavier. Give me a 6.4-6.5" display. 18/9 aspect ratio and round the corners a tiny bit but make it 10mm thick so it can fit a huge battery. And yeah no curved screen please.

Back Camera with jpg mode for photos overall except over 5x zoom where Samsung wins. Samsung is more consistent vs Vivo. s24U better against sunlight (even though other phones like Iphone 15P,P8P, or Vivo X100 Pro/Find X7 Ultra/Honor M6P seem even better). If everything went right the X90PP could get the better shots on main camera, but far too often it turned out bad. X90PP made better pictures from 3.8-5x zoom. The 3x zoom camera on S24U is it's worst camera. Ultrawide both phones really don't convince.

Gcam on X90PP was a mess with colors. On S24U gcam is a mess for quick shots and at night (not sure why it's so bad at nigh, gcam on X90PP at night was really what got the X90PP the draw here). That is after Vivo included the textured mode. I really couldn't be bothered with Natural and Vivid because both weren't my taste at all. Especially vivid (standard) mode on X90PP is horrible like in a comic. Natural mode for me was too bright without shadows, but with textured mode the camera finally became usable.

+++ S24 Ultra

Dsiplay in sun way better to read with the cutting of reflections by the new Gorilla glas. This makes a huge difference (of course cannot put a glass protector on as otherwise this advantage is gone and only slightly more brightness wins out)

Way better software. Wireless debugging doesn't turn of every few minutes, Rights are respected and not constantly given back to system apps. Debloating nearly without restrictions (only 1 app I cannot remove on S24U - gameservices - that I would like to debloat. Phone can be debloated to a degree that it doesn't phone home.

S24 Ultra basically anything that I want can be customized, routines allow for actions like use airplane mode as soon as wifi has good connection - while such things aren't possible on X90PP.

Selfie camera way better on S24U including autofocus that the X90PP misses. 4k60 video on selfie camera vs 1080/60 only on X90PP.

Photos with flash (also front Display flash) are much better on S24U. Vivo never dialled the flash. Though back camera flash as fill flash in sunshine is bad on both phones (as in basically not usable)

Warranty/software support/updates. Vivo is rock bottom here - cannot get worse while Samsung is industry leading. S24U gets updates faster than Pixel 8 while Security updates took ages on X90PP. And yeah 7 vs 3 years of updates.

AI - Samsung has loads of neat AI functions outside of the photo camera/gallery that make life easier. Vivo actually is better once you are inside China and speak/write Chinese and don't mind all your data ends up at your governement - then it has really crazy useful functions.. Otherwise outside China or in English Vivo AI is a joke.

Microphones - especially if using loudspeakers and not holding the phone at my ear. On the X90PP it was impossible for the other party to understand me if I used handless mode in a car. Or had to keep the phone very close at home while with S24U I can walk 2-3m away and other party still hears me clearly.

Loudspeakers - way better on S24U.

Support for Smartwatches/Unlock. Yeah X90PP was a ***** here. Garmin Fenix Watches worked but not for smart unlock. I don't have a Wear OS watch - but no support for them with Origin OS.

++ S24 Ultra

battery life is much better, especially during standby. Doesn't fluctuate from day to day (or month to month) - at least not so far. Better with both wifi and mobile data. However I expected a bit more from the S24U with mobile data. Somehow it doesn't fare that good (either bad antenna or like X90PP they cheaped out on the modem). And on the X90PP I had to deactivate the fingerprint reader to get somehow usable standby drain or in pocket drain. That's actually still the biggest difference. Walking around with the phone in my pocket the S24U uses <1%/h while the X90PP used 2-3%/h (yeah same apps running in background that constantly receive data). At home it's 1% vs 0.5%/h with mobile data or 0.8% vs 0.4%/h on wifi (0.3%/h in airplane mode with wifi on)

Better build quality vs the plastic back of the X90PP.

Much easier to hold in hand - I don't constantly get my fingers over the camera as on the X90PP. On X90PP I basically had to take of the case and wipe down cameras every time I want to get a decent shot. On S24U first thing the camera for right handed people are furthest away from your fingers, second stick out way less,

Warranty and service of course way easier to get. Battery replacements easy, should something break also possible to get it fixed (at home or in a shop)

Video overall is much better on S24U. It's much more consistent with options/modes.

Instagram, Snapchat, TikTok

S24U uploads / integrations look way better. Samsung worked with them to make sure the photos get uploaded in better quality same as from Iphones. Yeah not the phones fault but no matter how good your photo is - if uploaded to Instagram right now Iphones or S24 series is the only way to get good looking pics. So also Vivo X100 Ultra should it come out and have the greatest camera - it will still suck once uploaded to Instagram or snapchat due to the compression there.

Notifications that arrive always and reliably. Well most of the time without dark mode that worked with debloated vivo.pem - but not always.

+S24U

High quality cases from Spigen. Yeah not having Spigen cases to buy for X90PP was a real bummer. Could never find a quality case - either huge or no protection.

S-Pen - I rarely use it but to sign documents it's very handy. Sometime your scanned signature just isn't enough.

Overall the S24U really feels like a flagship without any real misses. The X90PP felt like flagship killer with big problem areas - and horrible software. The minus point for the S24U - you can get nearly all of it except the great display in sun, a tiny bit but not much worse camera system and 5 instead of 7 years software support with the S23U. S24U isn't a big step up from S23U since the S23U now also has all the AI integration. Battery life on S23U is as good as S24U and software too. Loudspeakers were actually a tiny bit better in low frequencies on S23U and cameras only from 5-10x clear advantage for S24U. Over 10x the S23U was a tiny bit better.

For battery life I'm a bit envious of the Honor Magic 6 Pro. That one just has best battery life right now on the market.

And on top S24U is due to Samsungs offers actually same price as the X100 Pro imported from China while the only clear advantages of X100 Pro over X90PP are battery life and in some points the camera. Honor Magic 6 Pro is more expensive. Yeah list price of Samsung is the most expensive - but Samsung has loads of offers while the other brands don't. Only in China it's of course the opposite. I guess the Vivo X100 Pro would win for me overall on camera for photos vs the S24U, would only slightly lose on battery (due to missing routines) but otherwise it's just the same mess as X90PP (or a tiny bit better with Funtouch).