A variety of things made the A1 a better overall fit for my unique mix of needs and interests. At the extreme high-end of current mirrorless cameras (>$5k without lenses) any major brand's latest flagship will very likely far exceed the needs of almost all users.
If you don't already know why you'd choose one brand's flagship over another, you probably shouldn't be considering any flagships. Frankly, these are highly specialized, complex and esoteric tools that are also incredibly expensive.
I recommend starting out with more mainstream models which are already supremely powerful and quite a bit less expensive than top-of-the-line models. Check out recent mainstream model reviews at DPReview.com - a highly credible source of objective comparisons.
It's a mature and highly competitive market that changes constantly. No major brand is overall "better" than another. It's more about finding the best fit between your needs, skills, budget and preferences.
An A1 would not be your first Sony camera even if you decided to buy Sony. It's a professional camera, and it's professional in the sense that it has features needed by professionals. It won't automatically make your pictures any better if you use it vs. something less expensive. If you have mad money, then go for it, but understand that you're more or less just burning cash for next to no reason.
For an amateur (i.e. anyone who is inclined to ask which camera to choose by brand name), all three brands have cameras that are more than sufficient to meet your needs. Among Sony full-frame devices, the current gen choice would be an A7 IV. Or if you're smart, you'd save yourself some money and buy an A7 III instead.
The main question is not "which brand makes the best camera" but, "which brand has the lenses I want." And the proper way to think about lenses for an amateur is to think about their speed, focal length (zoom level), price, and "convenience" -- weight, size, weather sealing.
I used to shoot with a D2X (dating myself here), and at the time Sony was not a serious contender at this level, at least among anyone I knew or any research I did. Everything was Nikon or Canon. Sony and Fujifilm seem to have some excellent cameras these days and I’m interested in what drew you to Sony versus the equivalent from Nikon or Canon?
Also, have the workflows improved on any of these in the last 15 years or is it still dump raw from the physical card to the computer and edit? Anything that lets you sync to a cloud storage when plugged in after a day of shooting?
Sony is very much a serious contender now. For a number of years they were the undisputed leader in a few areas, mainly value for money and autofocus performance. Everyone complains about Sony menu ergonomics although I personally don't find it to be much of a hindrance. There seems to be some evidence that canon and Nikon are catching up on some of the performance metrics.
On the other hand, for a long time Sony suffered from a shallower catalog of lenses but that grows less and less true by the day. For example they just released a trio of enthusiast compact prime lenses that according to reports I've read rival the best lenses of this type through history.
On the dpreview article about the camera you can see some spec sheet-level comparisons.
A variety of things made the A1 a better overall fit for my unique mix of needs and interests. At the extreme high-end of current mirrorless cameras (>$5k without lenses) any major brand's latest flagship will very likely far exceed the needs of almost all users.
If you don't already know why you'd choose one brand's flagship over another, you probably shouldn't be considering any flagships. Frankly, these are highly specialized, complex and esoteric tools that are also incredibly expensive.
I recommend starting out with more mainstream models which are already supremely powerful and quite a bit less expensive than top-of-the-line models. Check out recent mainstream model reviews at DPReview.com - a highly credible source of objective comparisons.
Professional digital cameras are a mature and highly competitive market that's changing frequently. No major brand is overall "better" than another. It's more about finding the best fit between your needs, skills, budget and preferences within a certain price and application segment. Any camera/lens combo represents a set of trade-offs between a dozen or more variables including light sensitivity, shutter speed, zoom, depth of field, video capabilities (resolution, frame rate, bit rate, compression, etc), weight, size and flexibility.