"Does a better camera take better pictures?"
Ah, the trick question. The answer is yes.
But the answer only applies if you (1) know what is lacking in your photos technically; (2) the new camera can help with that; (3) you take the time to learn what that is and how to apply that; and (4) you practice it so that it becomes second nature and muscle memory.
I'll give you a recent example that puts that in dramatic clarity. The Z9 with firmware C3.00 is a better camera than a Z9 with C1.00 firmware. The image sensor didn't change. The image processor didn't change. The EVF didn't change. What changed are a lot of small nuances in the focus system (which you need to learn and practice to take advantage of), and better abilities to customize the camera (which you need to study, pick the ones that work to your style, and practice to take advantage of). Those two things improved my photography with the Z9. Imagine what would happen if the sensor, processor, and EVF changed ;~).
Are my pictures dramatically better now? No. But I'm much more in control of the focus system, which is resulting in more keepers and is pulling out every last bit of detail those new Z lenses are capable of.
That said, if you aren't getting everything possible out of your current camera, all buying a new one does is kick the can further down the street.
"What's the best AF-area mode to use?"
Most people asking this question want a set-it-once-always-works answer. You're not going to get one. Not from me, not from the camera makers, not from anyone else that understands focus systems well.
We have multiple choices for a reason.
My usual answer to the question the way it's posed above is this: "I'd have to know what you're photographing, how you're photographing it, how you have configured and are using the camera, and whether you're comfortable with any complexity to refine your results." In other words, the answer is situational.
The most recent advanced cameras have all attracted attention from users for what is essentially Auto-area AF with Subject Detection. The marketing departments—particularly at Nikon and Sony as of late—are very good at the "it just works" voodoo answer, and people are swallowing that line, hook, and sinker.
The reality is far more nuanced. As I've mentioned several times, with the Nikon Z9 (and Sony A1 for that matter), I tend to perform a four finger dance with controls these days to get focus exactly where I want it. Note that I wrote "where I want it" and not "where the camera thinks is okay."
We have a lot of "good enough" going on in photography these days. And for many of you, that may be, indeed, good enough. Thus, the answer in those cases is Auto-area AF with Subject Detection, just like the camera makers keep suggesting. But then when you compare your work against someone who's extracting everything the cameras are capable of, you may find it wanting in terms of focus.
"Within depth of field" is not the same as "focus is exactly where it needed to be." Small drifts in the focus plane on a moving subject are not the same as keeping the focus plane on a specific part of a moving subject. I should point out that while I want that focus plane to move with a particular detail, I don't always get exactly that, even with my four-finger dance. But I get it more often than I would just pressing one button and letting the camera figure it out.
So I guess my answer to the question is a question: how precise do you want the focus to be, and are you willing to control something to get that?
The short answer is this: start with all auto, and then when you find that’s not working for something, use a smaller area ;~). This is true for Sony cameras (“try using a smaller focus area”) and Nikon cameras (“try using a smaller size for Wide-area AF”).
"My opinion is just as valid as yours."
Not a question, but what the heck, let me answer anyway.
It's fine to have an opinion. Everyone's entitled to theirs. But an opinion may not be particularly valid, may be based upon false assumptions or lackadaisical logic, and may not be supportable in a true debate.
So while everyone's entitled to their opinion, everyone is also entitled to not listen to your opinion. All of us tend to seek out informed observations; opinions that can clearly state how they were formed and what they are based upon. Over time, we evaluate whether those opinions had any relevancy or usefulness as more information becomes available. If we keep finding that someone's opinions have no basis in reality or turn out to be wrong, we'll stop listening to that person (at least we should; I know a lot of people who are failing at this).
I'm now going to do something I generally don't do: honk my own horn. I've been providing informed opinions about photography for over 30 years on the Internet. My following grew to over one million readers and has stayed relatively constant—without any advertising or promotion—for the last decade. I know from my emails and interactions with site readers that most of you are still "following" me after many years of reading my tl;dr observations and opinions. I'd like to think that's because my opinions have been useful to you (and/or have proven to be basically correct). If I were to think that my opinions weren't well considered and useful, I'd simply stop publishing them. However, it is annoying that people who are uninformed and unreliable are constantly—and I do mean constantly—trying to use the quoted construct to challenge me.
Most of the people I get this "my opinion is as valid as yours" construct from tend to be young. For them I'll just chalk it up to a relative of teenage angst ("my parents are against me"). The others tend to be angry fan boys (and note that I'm using the word "boy" for many people who are in their middle-age, which says something in itself, and yes, is an opinion ;~). Just remember, you can have an opinion and be wrong. Many of those challenging me constantly tend to be in this category.
Note I'm writing about "opinion" as opposed to "prediction". I don't know anyone that does predictions that is anywhere close to 100% correct. Heck economists are generally 100% wrong, but sometimes close. Indeed, 50% correct would be a really high hit rate for any specific prediction that is generated from scratch (as opposed to making a Yes/No choice on an offered option, where you should be 50% correct ;~). I tracked my predictions for years, and that ranged from 40% to 60% right. I no longer do much in the way of actual predictions (though I have something planned for late this year ;~).
"What are the best settings, e.g. ISO and aperture, for getting the highest sharpness and least noise?"
I can think of two answers to this question. The first answer is the theoretical absolute: the lowest numbered ISO on the camera and the tested aperture at which MTF is maximized. Personally, I ignore the theoretical absolute answer these days.
The second answer is: the ISO and aperture that net you the best results for the situation/conditions. Oh, oh. That means you have to think (and test). It seems that many budding photographers don't want to think, let alone test. They just want someone to tell them what to use and they then consider that golden advice that always applies. Often they really just want the camera set to "automatic". At least until they see the results, at which time they ask the question in bold, above.
Then there's the additional issue of whether we're talking about JPEG or raw. If you want out-of-camera-perfect JPEG results, you have a ton of other settings that you must get absolutely correct, including things like Picture Controls, Saturation, Contrast, Noise Reduction, White Balance, and these days, perhaps a dozen more. If you want perfect raw conversions, then things become more dependent upon your ability to recognize issues that arise during the capture and use the right settings to optimize the data that's recorded.
Let me me re-direct your question. What are you trying to photograph? What's the goal of that photograph? Sharpness and noise are attributes subordinate to your answer, not the answer themselves. When I look at an image the first thing that comes to mind isn't how sharp or noise-free it is, but whether the subject matter immediately draws me in. Heck, if the photo is of a sandstorm, how would I even tell it's noisy? ;~)
For what it's worth, most of the photos you find memorable are neither perfectly sharp nor noise-free. Some are sharp and noise-free, but that isn't the reason why remember them.
So try this mantra on for size: subject first, discipline second.
"Are the camera companies all going to go out of business?"
No one is immortal, though Disney sure tries hard at achieving that for all their assets.
I don't get the sense that any of the Japanese camera companies are in a problematic position at the moment, despite the strange and chaotic economic times we're in at the moment. The strength of the dollar and the overheated US market has helped them. They've shifted what parts they have available to the more expensive cameras they're selling, pushed much of that production into US distribution, and thus their gross profit margin numbers still look good. Demand is still higher than supply worldwide, so what shows up at stores tends to leave the store pretty quickly. Canon, Fujifilm, Nikon, and Sony are are all uncanny at survival techniques in tough times. In many ironic ways, the current situation is making them stronger, not weaker.
The real issue for the camera makers is this: growth. Despite pent-up market demand, there's no meaningful overall market growth at the moment. There probably will be for a short time once the supply chain gets more reliable. Much of the unserved demand is at the low end, which the camera companies seem to be weening themselves off of for the moment. The long term health of the camera companies is going to be dependent upon them achieving meaningful growth, though, and at the moment I'm not sure how or when that's going to happen. Still, we're far away from having to worry about that issue at the moment. All the companies have shifted themselves into a strong position at their current sizes, and many are showing some modest growth (though this is relative to a not-so-great previous year or two). But true market growth hasn't happened yet. We've been at 5.3m ILC units for a couple of years, and this year isn't going to be dramatically different, it appears.
