[Samsung Galaxy S23 Ultra] ajarosz:
So as promised, comparison. First I will compare JPG outputs. I took as well DNGs, and will prepare details comparison tomorrow in same manner.

Before I post result, - settings. In Camera Assistant HDR was on, smoothing to medium, priority set to quality, and new setting was off, so that focus is more important than speed. ExpertRAW, Stock and GCAM with no changes to brightness etc. For each of them before taking picture I was clicking on the book in the middle of the picture to make sure that focus is set same as well as exposure. Stock ones were taken in PRO mode (to save DNGs as well) and GCAM in Photo mode. No night mode, as it wasn't that dark yet. It was taken about an hour before sunset, so ideal conditions to have some light and some shadows at same time and to be quiet challenging. Today it was also quiet cloudy, so even outside it wasn't that bright.

As I want to be fully transparent, you can find all pictures here:

Amazon Directory with all photos

You can download them compare yourself.

There are 4 pictures in comparison. Order on all comparisons is same - first 12Mpix Stock app, then 50Mpix Stock app, ExpertRAW 50Mpix and GCAM (LMC 8.4 with JavaSabre v52 Sharp config).

First there is comparison of the scene as a whole, and then I'm taking a look at different parts of picture. So lets start.

0. Scene overall look:

GCAM is a bit darker (but is my personal setting and that can be changed as easy as default filter in Stock app, so that is applied for each photo). ExpertRAW is most contrasty nad HDR-like. Apart of that small differences between 12 and 50 stock, for me in favor to 50Mpix.

1. Details 1 - cosmetics by the window.

a) without resizing

I would say that GCAM despite lower resolution has best detail here. On the second from left container, you can read the bottom text, and that is possible only on that image. Then it is close call between all three for me, and it is hard to decide. What we can also spot here is different approach to processing images. Despite having Expert in the name, as that would suggest that maybe there is less processing and more for user to do play with/process later, it is quiet opposite. ExportRAW is by far most post processed one.

b) resizing to 12 Mpix

After resizing I think that ExpertRAW takes second place, 50Mpix stock third, 12 Mpix stock is third one.

2. Detail 2 - top corner of the headboard of the bed.

a) without resizing

It is quiet dark here, but only on GCAM one you can see clearly pattern of the wood. Also, because of Samsung's denoising corner between two walls is practically invisible. I think the worst one here is ExpertRAW as all details are just smudged out.

b) resizing to 12 Mpix

Here GCAM only GCAM shows details on both wood and curtain. On the output from ExpertRAW there is clearly pattern of what anoys me the most - there are some places where you can see curtain details, and some where it was just blurred with noise reduction. I would say 50 Mpix stock is second one here. ExportRAW for me is the worst one.

3. Detail 3 - blanket and pillow on the bed.

a) without resizing

Pattern is the same. Only GCAM retains small details and again ExpertRAW is the worst one.

b) resizing to 12 Mpix

After resizing again it is visible, that ExpertRAW has most drastic noise reduction and cannot decide, whether 12 Mpix or 50 Mpix Stock is better.

4. Detail 4 - top left corner of the image.

The only comparison in original size only. 12 Mpix stock shows some artifacts and color binding, 50 Mpix stock nosie and some smaller artifacts. Expert RAW is just a colorful mess and GCAM shows I think most noise, but no artifacts or issues with color binding. I think 50 Mpix Stock and GCAM are on pair here.

5. Detail 5 - trees outside.

a) no resizing

That picture shows, that despite tapping in exactly same place, there are small differences in the focus. What surprised me most here is how close to GCAM ExpertRAW here is. I would say details are on very similar level here. And that shows as well, how little difference is between 12 and 50 Mpix stock, when light conditions are far from perfect.

b) resizing to 12 Mpix

Again, look how close ExpertRAW and GCAM are. I would say that detail level is almost identical, there are small differences in rendering some textures, but rather tiny ones. Third is 50 Mpix stock, and then 12 Mpix one.

6. Detail 6 - books.

a) no resizing

I think GCAM is cleanest here, but then I would say very close is stock 50 Mpix. ExpertRAW is in some parts (book covers) good, while on the wooden cup stands it has just removed all details from the top. So.. I think it is even tie between 50Mpix Stock and ExpertRAW.

b) resizing to 12 Mpix

I think it is a tie between GCAM and 50Mpix stock, then ExpertRAW (only because of blurring some details) and then 12 Mpix stock.

c) bonus - resizing GCAM to mach 50 Mpix output from others.

I would say that is hard to tell which one is best here. I would vote for GCAM, as only on that image you can see wooden pattern on the cup stands, but even if ExpertRAW and 50Mpix stock are close.

EDIT: on the closer look, that pattern can be seen also on 12 Mpix Stock.

That is it for JPG comparison. I will prepare exactly the same with RAWs (rather DNGs) with initial look, and that can be recovered from them.

Also, just to check, I will snap same scene with Photo mode from stock app, to check whether there is difference between processing JPGs in Photo and PRO modes.

EDIT: did small comparison, and there is a difference between JPG postproduction from PRO and Photo sections on the main app. That one from PRO seems to be worse, and that might explain such big difference in my comparison. Tomorrow then instead of comparing DNGs, I will make another JPG comparison, but this time with JPGs taken with Photo mode.

Will skip ExpertRAW JPG, as clearly they are just bad.

ExpertRAW will return in comparison of DNGs.