[Rover]

Well, I think there are other things that may be important for the end user except the sensor size, otherwise everyone would have switched to Canon RP. :-)

[thxbb12]

I'm a bit torn regarding Fujifilm at the moment.

The X-H2 is darn cheap here in Oz at the moment. However, it's also as big as a Sony A7R x. The Fuji 16-55mm is tempting ... but then again ... it's as big as the Sony 24-105mm G.

https://camerasize.com/compact/#891.448,898.681,ha,t

Thus while I really like the new Fujis, there's a question of where's the point.

Fuji still makes quite a bit of sense if you're after a compact, yet high quality system.
For instance an X-T5 with any of these "new" Fuji primes has no equivalent in other systems: Fuji 14 f2.8, 23 f1.4, 33 f1.4, 56 WR f1.2
What I mean by "no equivalent" is that you get very high quality IQ, good DOF control and small sizes.
This new Sigma 18-50 f2.8 is in the same vein. It's very compact and good optically and it has no equivalent elsewhere (besides Sony APS-C).
I've contemplated other systems, notably, the Nikon Z system which has great primes and some compact zooms. I'd use it with the following lenses: 20 f1.8, 35 f1.8, 50 f1.8, 85 f1.8 and 24-70 f4. Size-wise a Fuji system makes more sense than this Z setup. Also, the Nikon system would not give me much better IQ, if any.

Also, when I want something super compact, I use a Fuji X-E4 along a Fuji 18 f2 or 27 f2.8. There is no equivalent to these combos either.

Klaus, given it seems you only used a Sony + 24-105 f4, it would make sense to consider a Nikon Z + 24-120 f4. This seems to be the most versatile and highest IQ combo at the moment. The 24-120 is about the same size as the Sony, has better reach, same speed and its IQ seems very very good (probably better than the Sony's).

[fotorrhoe]

...
On the other hand, the Sigma 18-50 is bright and very compact which is what I value the most these days.
Sure, the range is limited, but at the moment I mostly shoot with 3-4 primes: Fuji 18 f2, Viltrox 23 f1.4, Fuji 35 f1.4 and sometimes the Sigma 56 f1.4.
So the range covered by these lenses is enough for me.
I think the Sigma 18-50 along the Fuji 14 f2.8 and either 23 or 35 f1.4 would be perfect for me.

I have used the Sigma 18-50/2.8 along with the 11/1.8 in Sony-Land for a trip to Canada.
The two lenses are similar in dimensions and have the same filter threat.
I had more lenses with me but used these two most of the time in cities and internals.
You can have them in a jacket pocket on a body each just ready for the next shot. No way to compare with full frame.

[Klaus]

I'm a bit torn regarding Fujifilm at the moment.

The X-H2 is darn cheap here in Oz at the moment. However, it's also as big as a Sony A7R x. The Fuji 16-55mm is tempting ... but then again ... it's as big as the Sony 24-105mm G.

https://camerasize.com/compact/#891.448,898.681,ha,t

Thus while I really like the new Fujis, there's a question of where's the point.

Fuji still makes quite a bit of sense if you're after a compact, yet high quality system.
For instance an X-T5 with any of these "new" Fuji primes has no equivalent in other systems: Fuji 14 f2.8, 23 f1.4, 33 f1.4, 56 WR f1.2
What I mean by "no equivalent" is that you get very high quality IQ, good DOF control and small sizes.
This new Sigma 18-50 f2.8 is in the same vein. It's very compact and good optically and it has no equivalent elsewhere (besides Sony APS-C).
I've contemplated other systems, notably, the Nikon Z system which has great primes and some compact zooms. I'd use it with the following lenses: 20 f1.8, 35 f1.8, 50 f1.8, 85 f1.8 and 24-70 f4. Size-wise a Fuji system makes more sense than this Z setup. Also, the Nikon system would not give me much better IQ, if any.

Also, when I want something super compact, I use a Fuji X-E4 along a Fuji 18 f2 or 27 f2.8. There is no equivalent to these combos either.

Klaus, given it seems you only used a Sony + 24-105 f4, it would make sense to consider a Nikon Z + 24-120 f4. This seems to be the most versatile and highest IQ combo at the moment. The 24-120 is about the same size as the Sony, has better reach, same speed and its IQ seems very very good (probably better than the Sony's).

Yes, the Z 24-120 is tempting. However, the 24-105 G is a bank really. Even if the Nikkor is good, there can't be much between them really.

However, during the walks, I used the "Capture Camera Clip" ( https://www.peakdesign.com/products/capture/ ) from Peak Design on my backpack.

And the A7R II w/24-105mm was really at the limit in terms of size/weight.

I suppose that I will probably get myself a OM-5 w/12-45mm just for walking/trekking. I still have the 12-100 PRO which is also awesome.

[thxbb12]

I just ordered the Sigma 18-50 f2.8 for Fuji-X as it was on stock and on sale for 484 CHF (~495 euros).
I should receive it in a about 10 days, just in time for the family ski holidays :-)
I'll report my findings here by early 2023!